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Work toward developing a diffraction limited, single frequency, modulated transmitter suitable for coherent optical communication or direct detection communication is discussed. Diode pumped, monolithic Nd:YAG nonplanar ring oscillators were used as the carrier beam. An external modulation technique which can handle high optical powers, has moderate modulation voltage, and which can reach modulation rates of 1 GHz was invented. Semiconductor laser pumped solid-state lasers which have high output power (0.5 Watt) and which oscillate at a single frequency, in a diffraction limited beam, at the wavelength of 1.06 microns were built. A technique for phase modulating the laser output by 180 degrees with a 40-volt peak to peak driving voltage is demonstrated. This technique can be adapted for amplitude modulation of 100 percent with the same voltage. This technique makes use of a resonant bulk modulator, so it does not have the power handling limitations of guided wave modulators.

Work toward developing a diffraction limited, single frequency, modulated transmitter suitable for coherent optical communication or direct detection communication is discussed. Diode pumped, monolithic Nd:YAG nonplanar ring oscillators were used as the carrier beam. An external modulation technique which can handle high optical powers, has moderate modulation voltage, and which can reach modulation rates of 1 GHz was invented. Semiconductor laser pumped solid-state lasers which have high output power (0.5 Watt) and which oscillate at a single frequency, in a diffraction limited beam, at the wavelength of 1.06 microns were built. A technique for phase modulating the laser output by 180 degrees with a 40-volt peak to peak driving voltage is demonstrated. This technique can be adapted for amplitude modulation of 100 percent with the same voltage. This technique makes use of a resonant bulk modulator, so it does not have the power handling limitations of guided wave modulators.

Click here to view the University of Florida catalog record

Click here to view the University of Florida catalog record

192 p. 22 cm

Frequency comb assisted diode laser spectroscopy, employing both the accuracy of an optical frequency comb and the broad wavelength tuning range of a tunable diode laser, has been widely used in many applications. In this letter we present a novel method using cascaded frequency agile diode lasers, which allows extending the measurement bandwidth to 37.4 THz (1355 to 1630 nm) at MHz resolution with scanning speeds above 1 THz/s. It is demonstrated as a useful tool to characterize a broadband spectrum for molecular spectroscopy and in particular it enables to characterize the dispersion of integrated microresonators up to the fourth order.

We demonstrate a technique for locking the frequency of a tunable diode laser to a ring-cavity resonator. The resonator is stabilized to a diode laser which is in turn locked to an atomic transition, thus giving it absolute frequency calibration. The ring-cavity design has the principal advantage that there is no feedback destabilization of the laser. The cavity has a free-spectral range of 1.3 GHz and $Q$ of about 35, which gives robust locking of the laser. The locked laser is able to track large scans of the cavity.

We describe the operation of two GaN-based diode lasers for the laser spectroscopy of gallium at 403 nm and 417 nm. Their use in an external cavity configuration enabled the investigation of absorption spectroscopy in a gallium hollow cathode. We have analyzed the Doppler broadened profiles accounting for hyperfine and isotope structure and extracting both the temperature and densities of the neutral atomic sample produced in the glow discharge. We have also built a setup to produce a thermal atomic beam of gallium. Using the GaN-based diode lasers we have studied the laser induced fluorescence and hyperfine resolved spectra of gallium.

The License Elements of this Public License are Attribution, NonCommercial, and ShareAlike. ... Licensor means the individual(s) or entity(ies) granting rights under this Public License. NonCommercial means not primarily intended for or directed towards commercial advantage or monetary compensation. I will also be selling these soon. but fee free to make one for yourself and experiment with design. i have about 20-30 revisions, and a whole lot of learning costs. i'm placing faith in the community. just no selling, thanks for understanding. this design allows a much higher amount of air flow over laser cut parts and prevents flame, and large kerf areas. the blower is designed to inflate rafts and bed mattresses in about a minute. it says to run for only 20 minutes, but the blower is under very little load from the design and i have run it for hours at a time with no issue. (again this is because of low load level at output) this design allows high flow of air thru a large sized nozzle at the focus point of laser surface to move the particulate out of the way from the surface, and allow a longer laser life, and cleaner and deeper cuts. I am making this design open source for people interested in printing for themselves, or that have the skill and the patience to put all parts together. there is some assembly know how required, and costs of the air pump, and tubing. the nozzle assembly is in 4 parts, adjustable holder with tube inlet and zip tie holder connecting nozzle extender nozzle with flat end facing towards work surface nob that has a bolt inset to it for holding nozzle extender end in place. the tube is 1/2 inch tubing 5 to 6 feet in length . it has 2 inch wide painters tape wrapped around it to prevent that part from bending. then a zip tie is wrapped around and tightened so tube can not move. it can flex a little from the tightness, the tape wrapped around will prevent it from flattening. the clips go inside the bearing spaces, and help keep them tight to prevent slop. this is needed from additional strain of tubing and flexing. installing these clips increases accuracy of motion. the other end of tube is pressed into air adapter fitting piece. this piece is secured to the blower of the air pump, which should have two wraps of electrical tape wrapped around it before putting adapter on to keep it secure. the size at the nozzle end is 8mm by 8mm. this reduces load on motor and is optimized for maximum air flow over laser area. the flat end of the nozzle end piece should be facing down towards the surface of part to be cut or engraved. it should be between 1mm-6mm above the surface. as long as the flow of the nozzle is centered to the center of the laser flow should be ok. extra washers are included in my design so assembly can be moved in and out depending on amount of washers used, and the adapter has the ability to adjust up and down 1inch.

The License Elements of this Public License are Attribution, NonCommercial, and ShareAlike. ... Licensor means the individual(s) or entity(ies) granting rights under this Public License. NonCommercial means not primarily intended for or directed towards commercial advantage or monetary compensation. I will also be selling these soon. but fee free to make one for yourself and experiment with design. i have about 20-30 revisions, and a whole lot of learning costs. i'm placing faith in the community. just no selling, thanks for understanding. this design allows a much higher amount of air flow over laser cut parts and prevents flame, and large kerf areas. the blower is designed to inflate rafts and bed mattresses in about a minute. it says to run for only 20 minutes, but the blower is under very little load from the design and i have run it for hours at a time with no issue. (again this is because of low load level at output) this design allows high flow of air thru a large sized nozzle at the focus point of laser surface to move the particulate out of the way from the surface, and allow a longer laser life, and cleaner and deeper cuts. I am making this design open source for people interested in printing for themselves, or that have the skill and the patience to put all parts together. there is some assembly know how required, and costs of the air pump, and tubing. the nozzle assembly is in 4 parts, adjustable holder with tube inlet and zip tie holder connecting nozzle extender nozzle with flat end facing towards work surface nob that has a bolt inset to it for holding nozzle extender end in place. the tube is 1/2 inch tubing 5 to 6 feet in length . it has 2 inch wide painters tape wrapped around it to prevent that part from bending. then a zip tie is wrapped around and tightened so tube can not move. it can flex a little from the tightness, the tape wrapped around will prevent it from flattening. the clips go inside the bearing spaces, and help keep them tight to prevent slop. this is needed from additional strain of tubing and flexing. installing these clips increases accuracy of motion. the other end of tube is pressed into air adapter fitting piece. this piece is secured to the blower of the air pump, which should have two wraps of electrical tape wrapped around it before putting adapter on to keep it secure. the size at the nozzle end is 8mm by 8mm. this reduces load on motor and is optimized for maximum air flow over laser area. the flat end of the nozzle end piece should be facing down towards the surface of part to be cut or engraved. it should be between 1mm-6mm above the surface. as long as the flow of the nozzle is centered to the center of the laser flow should be ok. extra washers are included in my design so assembly can be moved in and out depending on amount of washers used, and the adapter has the ability to adjust up and down 1inch.

( 33x33mm version available here ) This is a Collinear Air Assist for Diode Laser Modules. It is made for 40x40 mm laser modules with a focusing ring of 21 mm. It can be mounted to the laser module without having to disassemble anything! It consists of two 3D printed parts; a housing and a focusing wheel. Print this item without support. Performs best in PET-G and ABS but may also work well with PLA. [RECOMMENDED RADIAL FAN] www.banggood.com/3Pcs-3D-Printer-12V-DC-50mm50mm-Blow-Radial-Cooling-Fan-p-1121554.html [REQUIRED HARDWARE] 1 pcs 33x33mm laser unit 1 pcs 50 mm radial fan 2 pcs M3 lock nuts (Alternatively regular M3 nuts) 1 pcs M3x20 and 1pcs M3x16 (Alternatively 2 pcs M3x20) 1 pcs small zip tie [LASER UNIT EXAMPLE] www.banggood.com/450nm-3500mW-3_5W-Blue-Laser-Module-With-TTL-Modulation-for-DIY-Laser-Cutter-Engraver-p-1103261.html [MOUNTING INSTRUCTIONS] 0) Remove the 19x2 mm support located under the flexible tab. 1) Push the focusing wheel around the focusing ring of the laser module. 2) Attach the small zip tie around the upper part of the focusing wheel and pull it tight to secure it around the focusing ring. 3) Insert M3 lock nut into the upper slot and insert M3x16 into it, screw it down until it just barely touches the plastic tab. 4) Move the housing up from underneath, sliding it over the focusing funnel until it pushes up against the laser module. 5) Tighten the M3x16 gently until feel the housing being secure on the laser module. 6) Insert M3 lock nut from the back into the screw hole for the fan. 7) Place the radial fan into position and insert M3x20 screw into the fan mounting hole and tighten. 8) Attach fan to power supply. [DONATIONS] If you find that the item improve your daily life, consider supporting the designer by sending a tip. Click "TIP DESIGNER" here. [BENEFITS OF AIR ASSIST] -Prevents smoke from degrading cutting power. -Clears some of the debris/charred material that has been cut from the cutting line which is useful if doing multiple passes. -Reduces the risk of material catching on fire. -Keeps debris and vaporized material from depositing on the lens of the laser.

We present a versatile, inexpensive and simple optical phase lock for applications in atomic physics experiments. Thanks to all-digital phase detection and implementation of beat frequency pre-scaling, the apparatus requires no microwave-range reference input, and permits phase locking at frequency differences ranging from sub-MHz to 7 GHz (and with minor extension, to 12 GHz). The locking range thus covers ground state hyperfine splittings of all alkali metals, which makes this system a universal tool for many experiments on coherent interaction between light and atoms.

The development and commercial application of high power diode laser arrays for use as solid-state laser pumps is described. Such solid-state laser pumps are significantly more efficient and reliable than conventional flash-lamps. This paper describes the design and fabrication of diode lasers emitting in the 780 - 900 nm spectral region, and discusses their performance and reliability. Typical measured performance parameters include electrical-to-optical power conversion efficiencies of 50 percent, narrow-band spectral emission of 2 to 3 nm FWHM, pulsed output power levels of 50 watts/bar with reliability values of over 2 billion shots to date (tests to be terminated after 10 billion shots), and reliable operation to pulse lengths of 1 ms. Pulse lengths up to 5 ms have been demonstrated at derated power levels, and CW performance at various power levels has been evaluated in a 'bar-in-groove' laser package. These high-power 1-cm stacked-bar arrays are now being manufactured for OEM use. Individual diode laser bars, ready for package-mounting by OEM customers, are being sold as commodity items. Commercial and medical applications of these laser arrays include solid-state laser pumping for metal-working, cutting, industrial measurement and control, ranging, wind-shear/atmospheric turbulence detection, X-ray generation, materials surface cleaning, microsurgery, ophthalmology, dermatology, and dental procedures.

Several materials systems are reviewed in attempt to determine the most favorable for use in the fabrication of diode lasers emitting in the 2- to 5-micron wavelength range. Eight possible systems, along with several of their variations, are identified among the III-V, IV-VI, and II-VI semiconductors. All meet the following criteria: optical and carrier confinement can be obtained, a significant portion of the desired wavelength range can be achieved, and the layers that are required to fabricate a double-heterostructure (DH) laser can be lattice matched to a suitable substrate. The performance of III-V laser devices is limited by Auger recombination and free-carrier absorption. The role of the valence band structure in these effects is of particular importance. The III-V system identified as the most promising is GaInAsSb/AlGaAsSb/GaSb, with the quaternary alloy GaInAsSb for the active layer, the quaternary alloy AlGaAsSb for the cladding layers, and GaSb for the substrate. This system offers substrate availability, a wide range of wavelengths, good metallurgical properties and favorable device physics. In this system, DH lasers emitting at approximately 2.3 micron have been operated CW at room temperature with threshold current densities as low as 1.5 A/sq cm, and differential quantum efficiencies as high as 18 percent per facet have been obtained in pulsed room- temperature operation. According to theoretical projections, the threshold current density of such GaInAsSb/AlGaASSb/GaSb lasers will increase with increasing wavelength because of increased Auger recombination and free-carrier absorption. (r.h.)

This report results from a contract tasking Imperial College of Science, Technology, and Medicine as follows: The contractor will investigate the feasibility of obtaining diffraction limited beam quality from high power semiconductor amplifier devices by incorporating a novel self adaptive resonator design.

The goals of this program were: development of high-power, cw diode-laser-array-pumped, Nd:YAG lasers, and efficient nonlinear frequency conversion of their output. Two minislab laser heads constructed as a single high power dual-head oscillator (96W, multi-mode) were operated separately to support Q-switched and cw nonlinear frequency conversion studies and single-frequency injection-locking studies and the start of cw amplifier research. A cw singly resonant optical parametric oscillator (SRO) utilizing bulk periodically poled LiNbO3 (PPLN) for tunable mid-IR radiation using the Q-switched laser as the pump was developed, and SHG output at 532 nm was increased from 800 mW average power (15 KHz rep rate) to 1300 mW average power (8.4 KHz rep rate). Coherent laser radar with high-power, high-coherence sources was pursued through a highly-coherent master oscillator cw power amplifier approach. We operated one laser head as a (1OW TEM00) oscillator and the second laser head as a triple-pass amplifier achieving 26 W TEM00 output. More extensive experiments on cw diode-laser pumped laser amplifiers for high-power, high-coherence sources were carried out to test the ability of theoretical modeling to predict amplifier output power.

In this paper we review recent progress achieved in our development of type-1 GaInAsSb/AlGaAsSb quantum-well (QW) lasers with emission wavelength in the 1.74 - 2.34 micrometers range. Triple-QW (3-QW) and single-QW (SQW) diode lasers having broadened waveguide design emitting around 2.26 micrometers have been studied in particular. Comparing the two designs we have find that the threshold current density at infinite cavity length as well as the transparency current density scale with the number of QWs. Maximum cw operating temperature exceeding 50 deg C and 90 deg C has been obtained for ridge waveguide lasers emitting above and below 2 micrometers, respectively. Ridge waveguide diode lasers emitting at 1.94 micrometers exhibited internal quantum efficiencies in excess of 77%, internal losses of 6/cm, and threshold current density at infinite cavity length as low as 121 A/sq cm reflecting the superior quality of our diode lasers, all values recorded at 280 K. A high characteristic temperature T(sub O) of 179 K for the threshold current along with a value of T1 = 433 K for the characteristic temperature of the external efficiency have been attained for the 250 - 280 K temperature interval. Room temperature cw output powers exceeding 1.7 W have been demonstrated for broad area single element devices with high-reflection/antireflection coated mirror facets, mounted epi-side down. The latter result is a proof for the high power capabilities of these GaSb-based mid-ir diode lasers.

This thesis discusses the work to make ultrashort pulsed lasers smaller and more economical. While sharing many of the basic properties of normal beam optics there are some specific properties in both creating and exploiting those pulses that must be understood. The discussion will focus on mode locking as the primary way of producing ultrashort pulses. Particular attention will be paid to intracavity group velocity dispersion and how to correct it inside the cavity. The discussion then turns to the basis of our work including initial cavity design and component selection with focus on the specific crystals used in the solid state laser. The rest of the experiment setup is based on evolution of the designs in order to get the systems lasing and then mode locked. Results from the work on the small cavity systems are compared to data taken from a commercial titanium-sapphire laser with emphasis on current measurement techniques. Overall conclusions include the impact of both equipment and the crystals used in the solid state cavity to generate ultrashort pulses. While not fully successful, the groundwork has been laid for future research.

A high power channeled substrate planar AlGaAs diode laser with an emission wavelength of 8600 to 8800 A was developed. The optoelectronic behavior (power current, single spatial and spectral behavior, far field characteristics, modulation, and astigmatism properties) and results of computer modeling studies on the performance of the laser are discussed. Lifetest data on these devices at high output power levels is also included. In addition, a new type of channeled substrate planar laser utilizing a Bragg grating to stabilize the longitudinal mode was demonstrated. The fabrication procedures and optoelectronic properties of this new diode laser are described.

Click here to view the University of Florida catalog record

This paper presents viewgraphs on Far-infrared Antimony based quantum well systems pumped by near infrared diode lasers.

We report on the combined action of a cw diode laser and a train of ultrashort pulses when each of them drives one step of the 5S-5P-5D two-photon transition in rubidium vapor. The fluorescence from the 6P_{3/2} state is detected for a fixed repetition rate of the femtosecond laser while the cw-laser frequency is scanned over the rubidium D_{2} lines. This scheme allows for a velocity selective spectroscopy in a large spectral range including the 5D_{3/2} and 5D_{5/2} states. The results are well described in a simplified frequency domain picture, considering the interaction of each velocity group with the cw laser and a single mode of the frequency comb.

We report on the combined action of a cw diode laser and a train of ultrashort pulses when each of them drives one step of the 5S-5P-5D two-photon transition in rubidium vapor. The fluorescence from the 6P_{3/2} state is detected for a fixed repetition rate of the femtosecond laser while the cw-laser frequency is scanned over the rubidium D_{2} lines. This scheme allows for a velocity selective spectroscopy in a large spectral range including the 5D_{3/2} and 5D_{5/2} states. The results are well described in a simplified frequency domain picture, considering the interaction of each velocity group with the cw laser and a single mode of the frequency comb.

The overall program objective is to develop an on-chip UV mu-laser that is able to excite fluorescence from bio-aerosols. This objective requires that we design mu-lasers that have low threshold with directionality in their emission. Hence, there is a need to optimize the pumping geometry of the mu-disk and the shape for maximum output efficiency. The resulting non-circular shapes necessitated that we understand some principles of chaos theory.

The transverse pumping of solid-state lasers in a cylindrical rod configuration has been explored both analytically and experimentally. The pumping configuration coupled diode laser arrays to the laser rod through slits in a geometrically reflecting chamber using simple lenses. 50 W of diode lasers in the form of ten 5 W, 1 cm bars were used to pump 2 cm of a Nd: YAG rod. Output powers for 3 mm and 4 mm diameter rods were compared with and without the reflecting multi-pass pump cavity. An increase in output power of 35% was achieved by using the multi-pass cavity, approximately in agreement with expectation. Although threshold pump powers agreed with our analysis, slope efficiencies were much lower than expected, and output powers seemed to saturate at 2.5 W with 35 W incident on the rod. Detailed data on the beam profiles and wavelength distributions of the diode laser bars is also presented.

A generalized theoretical formalism is derived that optimizes the doping profile of semiconductor diode lasers and amplifiers for maximum power conversion efficiency by balancing resistive and free-carrier absorption losses. The doping profile is shown to be the same function of optical mode profile, free-carrier absorption cross-section, and carrier mobility, independent of the specific model used for efficiency. The magnitude of the doping is dictated by the chosen efficiency model and the device design and operating conditions. The derived formalism can be applied to any particular model of diode emitter efficiency and expressed entirely in terms of measurable parameters. In addition, as a consequence of this analysis, a figure of merit is introduced that quantifies the ability of a waveguide to perform as a high efficiency laser or amplifier.

Two laser pumped Nd:YAG lasers were frequency stabilized to a commercial 6.327 GHz free spectral range Fabry-Perot interferometer yielding a best case beatnote linewidth of 330 MHz. In addition, a Fabry-Perot interferometer with a free spectral range of 680 MHz, a linewidth of 25 kHz, and a finesse of 27,500 was built, and when it was substituted in place of the commercial interferometer, it produced a robust and easily repeatable beatnote linewidth of 700 MHz.

The reliability and lifetime of laser diodes is critical to space missions. The Nuclear Spectroscopic Telescope Array (NuSTAR) mission includes a metrology system that is based upon laser diodes. An operational test facility has been developed to qualify and select, by mission standards, laser diodes that will survive the intended space environment and mission lifetime. The facility is situated in an electrostatic discharge (ESD) certified clean-room and consist of an enclosed temperature-controlled stage that can accommodate up to 20 laser diodes. The facility is designed to characterize a single laser diode, in addition to conducting laser lifetime testing on up to 20 laser diodes simultaneously. A standard laser current driver is used to drive a single laser diode. Laser diode current, voltage, power, and wavelength are measured for each laser diode, and a method of selecting the most adequate laser diodes for space deployment is implemented. The method consists of creating histograms of laser threshold currents, powers at a designated current, and wavelengths at designated power. From these histograms, the laser diodes that illustrate a performance that is outside the normal are rejected and the remaining lasers are considered spaceborne candidates. To perform laser lifetime testing, the facility is equipped with 20 custom laser drivers that were designed and built by California Institute of Technology specifically to drive NuSTAR metrology lasers. The laser drivers can be operated in constant-current mode or alternating-current mode. Situated inside the enclosure, in front of the laser diodes, are 20 power-meter heads to record laser power throughout the duration of lifetime testing. Prior to connecting a laser diode to the current source for characterization and lifetime testing, a background program is initiated to collect current, voltage, and resistance. This backstage data collection enables the operational test facility to have full laser diode traceablity.

The reliability and lifetime of laser diodes is critical to space missions. The Nuclear Spectroscopic Telescope Array (NuSTAR) mission includes a metrology system that is based upon laser diodes. An operational test facility has been developed to qualify and select, by mission standards, laser diodes that will survive the intended space environment and mission lifetime. The facility is situated in an electrostatic discharge (ESD) certified clean-room and consist of an enclosed temperature-controlled stage that can accommodate up to 20 laser diodes. The facility is designed to characterize a single laser diode, in addition to conducting laser lifetime testing on up to 20 laser diodes simultaneously. A standard laser current driver is used to drive a single laser diode. Laser diode current, voltage, power, and wavelength are measured for each laser diode, and a method of selecting the most adequate laser diodes for space deployment is implemented. The method consists of creating histograms of laser threshold currents, powers at a designated current, and wavelengths at designated power. From these histograms, the laser diodes that illustrate a performance that is outside the normal are rejected and the remaining lasers are considered spaceborne candidates. To perform laser lifetime testing, the facility is equipped with 20 custom laser drivers that were designed and built by California Institute of Technology specifically to drive NuSTAR metrology lasers. The laser drivers can be operated in constant-current mode or alternating-current mode. Situated inside the enclosure, in front of the laser diodes, are 20 power-meter heads to record laser power throughout the duration of lifetime testing. Prior to connecting a laser diode to the current source for characterization and lifetime testing, a background program is initiated to collect current, voltage, and resistance. This backstage data collection enables the operational test facility to have full laser diode traceablity.

This article is from Journal of Dental Research, Dental Clinics, Dental Prospects , volume 7 . Abstract Background and aims: Considering the importance of disinfecting dentin after cavity preparation and the possible effect of disinfection methods on induction of various reactions between the tooth structure and the adhesive restorative material, the aim of the present study was to evaluate microleakage of composite resin restorations after disinfecting the prepared dentin surface with Nd:YAG and Diode lasers and photodynamic therapy. Materials and methods: Standard Class V cavities were prepared on buccal surfaces of 96 sound bovine teeth. The samples were randomly divided into 4 groups based on the disinfection method: Group 1: Nd:YAG laser; Group 2: Diode laser; Group 3: photodynamic therapy; and Group 4: the control. Self-etch bonding agent (Clearfil SE Bond) was applied and all the cavities were restored with composite resin (Z100). After thermocycling and immersing in 0.5% basic fuchsin, the samples were prepared for microleakage evaluation under a stereomicroscope. Data was analyzed with Kruskal-Wallis and Wilcoxon signed-rank tests at P 0.05). There were no significant differences in microleakage between the occlusal and gingival margins in the Nd:YAG laser group (P>0.05). In the other groups, microleakage at gingival margins was significantly higher than that at the occlusal margins (P

The transverse pumping of a cylindrical laser rod such as YAG by a set of diode laser arrays equally spaced in angle around the rod has been analyzed using both geometrical and wave optics. Between the pump sources and the laser rod there may be an arbitrary number of concentric media, transparent to the pump light; and in addition modification of the diode laser radiation patterns will require other optical components. The analysis accommodates both of these complications, even when the optics in front of the diodes do not image point sources to points. It is sufficient to be able to describe the intensity and ray directions in finite apertures concentric with the rod. One result of the cylindrical geometry is the formation of caustics which have infinite intensity in the geometrical optics approximation; and it is necessary to develop a wave optics theory to predict the intensity in the neighborhood of the caustic edge of the illuminated region inside the laser rod. The wave theory first uses the geometrical optics method to calculate the amplitude and phase just inside the rod's surface, which serves then as an aperture distribution function describing the source of Huygens wavelets in the computation of a diffraction integral.

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Novel designs of the mid-infrared GaSb-based diode lasers were studied including those based on triple layer quantum well active regions, metamorphic virtual substrate and cascade pumping scheme. Cascade pumping of type-I quantum well gain section opened the whole new avenue of the mid-infrared diode laser development with the prospect of multifold improvement of the device characteristics. Cascade pumping was achieved utilizing efficient interband tunneling through leaky window in band alignment at GaSb/InAs heterointerface. The 100% efficient carrier recycling between stages was confirmed by twofold increase light-current characteristics slope of two-stage 2.4-3.3 m cascade lasers as compared to reference single-stage devices. The cascade pumping scheme reduced threshold current density of high power type-I quantum well GaSb-based ? 3 micron diode lasers down to 100 A/sq cm at room temperature. Devices with densely stacked two and three gain stages and 100-micron-wide aperture demonstrated peak power conversion efficiency of 16% and continuous wave output power of 960 mW. Corresponding narrow ridge lasers demonstrated above 100 mW of output power. Devices

Constricted double-heterojunction (CDH) lasers are presented as the class of single-mode nonplanar-substrate devices for which the lasing cavity is on the least resistive electrical path between the contact and the substrate. Various types of CDH structures are considered under three general topics: liquid-phase epitaxy over channeled substrates, lateral mode control, and current control in nonplanar-substrate devices. Ridge-guide CDH lasers have positive-index lateral-mode confinement and provide: single-mode CW operation to 7 mW/facet at room temperature and to 3 mW/facet at 150 C; light-current characteristics with second-harmonic distortion as low as -57 dB below the fundamental level; threshold-current temperature coefficients, as high as 375 C (pulsed) and 310 C (CW); constant external differential quantum efficiency to 100 C; and lasing operation to 170 C CW and 280 C pulsed. Semileakyguide CDH lasers have an asymmetric leaky cavity for lateral-mode confinement and provide single-mode operation to 15 to 20 mW/facet CW and to 50 mW/facet at 50% duty cycle. Modulation characteristics and preliminary reliability data are discussed.

Constricted double-heterojunction (CDH) lasers are presented as the class of single-mode nonplanar-substrate devices for which the lasing cavity is on the least resistive electrical path between the contact and the substrate. Various types of CDH structures are considered under three general topics: liquid-phase epitaxy over channeled substrates, lateral mode control, and current control in nonplanar-substrate devices. Ridge-guide CDH lasers have positive-index lateral-mode confinement and provide: single-mode CW operation to 7 mW/facet at room temperature and to 3 mW/facet at 150 C; light-current characteristics with second-harmonic distortion as low as -57 dB below the fundamental level; threshold-current temperature coefficients, as high as 375 C (pulsed) and 310 C (CW); constant external differential quantum efficiency to 100 C; and lasing operation to 170 C CW and 280 C pulsed. Semileakyguide CDH lasers have an asymmetric leaky cavity for lateral-mode confinement and provide single-mode operation to 15 to 20 mW/facet CW and to 50 mW/facet at 50% duty cycle. Modulation characteristics and preliminary reliability data are discussed.

We report the investigation of a collimated blue light generated in rubidium vapor due to the combined action of an ultrashort pulse train and a cw diode laser. Each step of the two-photon transition 5S - 5P$_{3/2}$ - 5D is excited by one of the lasers, and the induced coherence between the 5S and 6P$_{3/2}$ states is responsible for generating the blue beam. Measurements of the excitation spectrum reveal the frequency comb structure, indicating that each individual mode is responsible for inducing a nonlinear process. The strong signal dependency on the atomic density is characterized by a sharp growth and rapid saturation.

( 40x40mm version available here ) This is a Collinear Air Assist for Diode Laser Modules. It is made for 33x33 mm laser modules with a focusing ring of 16 mm. It can be mounted to the laser module without having to disassemble anything! It consists of two 3D printed parts; a housing and a focusing wheel. Print this item without support. Performs best in PET-G and ABS but may also work well with PLA. [RECOMMENDED RADIAL FAN] www.banggood.com/3Pcs-3D-Printer-12V-DC-50mm50mm-Blow-Radial-Cooling-Fan-p-1121554.html [REQUIRED HARDWARE] 1 pcs 33x33mm laser unit 1 pcs 50 mm radial fan 2 pcs M3 lock nuts (Alternatively regular M3 nuts) 1 pcs M3x20 and 1pcs M3x16 (Alternatively 2 pcs M3x20) 1 pcs small zip tie [LASER UNIT EXAMPLE] www.banggood.com/445nm-2_5W-2500mW-Blue-Laser-Module-With-Heatsink-For-DIY-Laser-Cutter-Engraver-p-993521.html [MOUNTING INSTRUCTIONS] 0) Remove the 19x2 mm support located under the flexible tab. 1) Push the focusing wheel around the focusing ring of the laser module. 2) Attach the small zip tie around the upper part of the focusing wheel and pull it tight to secure it around the focusing ring. 3) Insert M3 lock nut into the upper slot and insert M3x16 into it, screw it down until it just barely touches the plastic tab. 4) Move the housing up from underneath, sliding it over the focusing funnel until it pushes up against the laser module. 5) Tighten the M3x16 gently until feel the housing being secure on the laser module. 6) Insert M3 lock nut from the back into the screw hole for the fan. 7) Place the radial fan into position and insert M3x20 screw into the fan mounting hole and tighten. 8) Attach fan to power supply. [DONATIONS] If you find that the item improve your daily life, consider supporting the designer by sending a tip. Click "TIP DESIGNER" here. [BENEFITS OF AIR ASSIST] -Prevents smoke from degrading cutting power. -Clears some of the debris/charred material that has been cut from the cutting line which is useful if doing multiple passes. -Reduces the risk of material catching on fire. -Keeps debris and vaporized material from depositing on the lens of the laser.

Research on a proposed storage diode laser is described. The objectives are (1) completion of design theory (2) basic parameter measurements (3) experimental proof (4) fabrication of effective devices. The desirability of such a device in many potential applications is discussed. The design theory is presented in detail. Four possible storage diode laser configurations are described, of which the most promising involves a low current storage pulse and high current trigger pulse in a long lifetime material. The possibility of obtaining long lifetime by the shift from direct to indirect transition is discussed. Negative experimental results with extreme high current pulses in germanium and silicon are presented. Reverse emission of gallium arsenide and the shift of the absorption edge in germanium are described. The design of diode laser pulsers is reviewed in general. Three specific circuit configurations are presented. An electrical double pulser is described. The technology of image converters and coolers used is described.

The growth condition for fabricating 1.5 micron lasers using LPE techniques has been established. High power performance and external quantum efficiency of the laser are studied. Keywords include: Semiconductor lasers, GAInAsP/InP, 1.5 microns.

The contracted program to develop an atomic absorption vapor monitoring system began as scheduled on 9/1/94. Initial efforts focused on spectroscopic monitoring of low density yttrium vapor using a fundamental frequency laser. A test-bed system for frequency doubling was assembled. Parts were ordered for the construction of the prototype system. jg p.2

We demonstrate passive harmonic mode-locking of a quantum well laser diode designed to support a discrete comb of Fabry-Perot modes. Spectral filtering of the mode spectrum was achieved using a non-periodic patterning of the cavity effective index. By selecting six modes spaced at twice the fundamental mode spacing, near-transform limited pulsed output with 2 ps pulse duration was obtained at a repetition rate of 100 GHz.

NAS 1.26:3045 Digitized from IA1177305-04-0019 , IA1177305-04-0020 .

NAS 1.26:3045 Digitized from IA1177305-04-0019 , IA1177305-04-0020 .

We show that nonlinear dynamics in diode lasers with optical injection leads to frequency tunable microwave sidebands which are suitable for atomic physics experiments. We demonstrate the applicability of the sidebands in an experiment where rubidium atoms are magneto-optically trapped with both the trap and the re-pump optical frequencies derived from one optically injected laser. We find linewidth narrowing in the optical spectrum of the injected laser at both the injection frequency and the sideband frequency. With strong optical injection which leads to frequency locking we find a complete linewidth transfer from the master to the slave. Further applications are discussed.

It is shown that optical synthesis of terahertz and millimeter-wave frequencies can be achieved using two-mode and mode-locked discrete mode diode lasers. These edge-emitting devices incorporate a spatially varying refractive index profile which is designed according to the spectral output desired of the laser. We first demonstrate a device which supports two primary modes simultaneously with high spectral purity. In this case sinusoidal modulation of the optical intensity at terahertz frequencies can be obtained. Cross saturation of the material gain in quantum well lasers prevents simultaneous lasing of two modes with spacings in the millimeter-wave region. We show finally that by mode-locking of devices that are designed to support a minimal set of four primary modes, we obtain a sinusoidal modulation of the optical intensity in this frequency region.

We numerically investigate the complex nonlinear dynamics for two independently coupled laser systems consisting of (i) mutually delay-coupled edge emitting diode lasers and (ii) injection-locked quantum nano-structures lasers. A comparative study in dependence on the dynamical role of alpha parameter, which determine the phase-amplitude coupling of the optical field, in both the cases is probed. The variation of alpha lead to conspicuous changes in the dynamics of both the systems, which are characterized and investigated as a function of optical injection strength for the fixed coupled-cavity delay time. Our analysis is based on the observation that the cross-correlation and bifurcation measures unveil the signature of enhancement of amplitude-death islands in which the coupled lasers mutually stay in stable phase-locked states. In addition, we provide a qualitative understanding of the physical mechanisms underlying the observed dynamical behavior and its dependence on alpha. The amplitude death and the existence of multiple amplitude death islands could be implemented for applications including diode lasers stabilization.

We have developed external-cavity diode lasers, where the wavelength selection is assured by a low loss interference filter instead of the common diffraction grating. The filter allows a linear cavity design reducing the sensitivity of the wavelength and the external cavity feedback against misalignment. By separating the feedback and wavelength selection functions, both can be optimized independently leading to an increased tunability of the laser. The design is employed for the generation of laser light at 698, 780 and 852 nm. Its characteristics make it a well suited candidate for space-born lasers.

This contract funded a major effort in bringing to maturity, a first-principles theory of semiconductor lasers and amplifiers based on a fully microscopic description of the light semiconductor material coupling. Significant breakthroughs were made at the microscopic physics level by explicitly including all of the relevant excited bands in the active region of the device and obtaining quantitative agreement with gain/index and linewidth enhancement spectra measured for a variety of Quantum Well structures at the Air Force Research Laboratory, Albuquerque, NM. The full nonlinear pde model for high power wide aperture semiconductor lasers was reformulated theoretically so as to take advantage of speed and excellent parallel scaling of our ONYS2 in-house supercomputer. Resulting from this is the first interactive simulator for designing new generations of high brightness semiconductor devices. We were able to begin building a fully interactive platform-independent optoelectronic simulator which should have a major impact on designing sophisticated telecoms systems. Funding also allows major inroads in explaining the novel creation of an optically turbulent atmospheric light guide.

Initial operation of the tunable diode lasers (TDL) showed that it was not possible to adjust the wavenumber to one selected a priori in the TDL tuning range. During operation, the operating point would change by 0.1/cm over the longer term with even larger changes occurring during some thermal cycles. Most changes during thermal cycling required using lower temperatures and higher currents to reach the former wavenumber (when it could be reached). In many cases, an operating point could be selected by changing TDL current and temperature to give both the desired wavenumber and most of the power in a single mode. The selection procedure had to be used after each thermal cycling. Wavenumber nonlinearities of about 10% over a 0.5 cm tuning range were observed. Diagnostics of the single mode selected by a grating monochromator showed wavenumber fine structure under certain operating conditions. The characteristics due to the TDL environment included short term wavenumber stability, the instrument lineshape function, and intermediate term wavenumber stability.

The method and the apparatus for identifying excess-noise regions in tunable diode lasers are described. These diode lasers exhibit regions of excess noise as their wavelength is tuned. If a tunable diode laser is to be used as a local oscillator in a superheterodyne optical receiver, these excess-noise regions severely degrade the performance of the receiver. Measurement results for several tunable diode lasers are given. These results indicate that excess noise is not necessarily associated with a particular wavelength, and that it is possible to select temperature and injection current such that the most ideal performance is achieved.