In order to further increase the fiber-coupled module output power, eight cm-bar 808 nm laser diodes, 50 w output each, fiber coupling module has been designed by using ZEMAX optical design software through space and polarization beam combination method. The core diameter of output fiber is 400 μm with a numerical aperture of 0.22. Finally the fiber output power is 350.2 W, with a coupling efficiency of 87.6%.
All-dielectric film narrow band filter is widely used in laser system owing to its excellent optical capability,
manufacturability and environmental adaptability. But 905nm infrared semiconductor laser system have large divergence
angel so we designed entrance light cone angle 905nm narrow band filter. And center wavelength shift, due to entrance
light cone angle, affects its spectral selective power seriously. In order to reduce these impacts, an informal dielectric
film narrowband filter is designed. Changes of transmission characteristics with oblique incidence of Gaussian beam of
uneven illumination are analyzed. The relationship between the angle of incidence and the central wavelength shift
quantificational are Solved. A ± 30 ° incident 905nm narrowband filter was fabricated. Between 880nm and 950nm, the
average transmittance is above 90%, and at the cut-off band the average transmittance is below 1%.
Semiconductor lasers at wavelengths around 1.3μm are widely used for optic communications. For GaInNAs, the
incorporation of nitrogen in the active layer can reduce the band-gap energy and allow emission wavelengths as long as
1.3μm. Ridge waveguide GaInNAs strain single-quantum-well lasers were fabricated with pulsed anodic oxidation
(PAO). Using the technology PAO, we prevented the damage from the ion bombardment in the procedure of sputtering
silicon dioxide used for building the insulating film. The output power of the laser with a wavelength of 1.31μm reached
14mW in CW mode at room temperature. The threshold-current was 18mA and its density was 360A/cm<sup>2</sup>. The
characteristic temperature of lasers was 135.1K and the quantum efficiency reached 76%.
High power laser bars become more and more important for pumping of solid-state lasers, medical applications, optical data storage, display, and material processing such as welding, cutting, or surface treatment. Diode lasers array emitting at 980 nm has excited considerable interest as optical pumping source for the Erbium-doped fiber amplifier (EDFA), cladding pumped fiber amplifiers or fiber lasers. A high power multi-mode 980 nm InGaAs laser arrays grown by MBE are reported. Non-absorbing windows are integrated at the ends of the cavity to decrease the light density on the mirror for high power operation. A QCW output power of 64.8 W for lasers array with coated facets is achieved. The threshold current is 7.5 A. The lasing spectrum is peaked at 978 nm with a FWHM of 2.5 nm.
A novel structure for high peak power output of semiconductor lasers has been designed with a weak optical absorption region near cavity facet and a low optical energy density distribution on both front and back cavity facets has been realized simultaneously. The device has been fabricated with a standard MBE grown AlGaAs/GaAs material wafer, and a stack assembly of five laser chips has been finally obtained. The measured stack has a maximum peak power output of 300W with a whole emitting aperture of 2×0.5mm<sup>2</sup> and a satisfactory farfield (θ⊥) output property is also achieved with θ⊥ of 31<sup>o</sup>.
AlGaAs/GaAs material diode lasers grown by MOCVD using TBA as the group-V source and N<sub>2</sub> as the carrier gas, was reported. Lasing has been successfully achieved with a low threshold current density of 506 A/cm<sup>2</sup>.
High power InGaAsN triple-quantum-well strain-compensated lasers grown by metal organic chemical vapor deposition (MOCVD) were fabricated with pulsed anodic oxidation. A maximum light power output of 304 mW was obtained from a 10-μm stripe width uncoated laser diode in continuous wave (CW) mode at room temperature. The characteristic temperature of the lasers was 138 K.
This paper presents the structure design and fabrication technology of 850nm wavelength high power wide spectrum Superluminescent Diodes (SLDs) as non-coherent light source, for the application of fiber gyroscope and other areas. Quantum Well epitaxial structure, unpumped absorbing region structure and facet coating methods have been adopted for enhancing the gain coefficient, output power and the reduction or elimination of lasing oscillation. As typical device performance results, SLDs have been demonstrated with central wavelength of 848-851nm, spectrum FWHM no less than 20nm, and no less than 7mW output under 120mA injection current. The devices operated up to 100°C.
This paper presents the structure design and fabrication technology of 850nm superluminescent Diodes (SLDs).Various ways have been tried for the suppression of F-P lasing oscillation to realize superluminescence: Tilted-stripe structure, tandem-type structure and non-injection section near the rear facet are introduced. Three structures are also compared and combined with each other. The device not lasing at maximum injection current 200mA is realized. At injection current of 150mA, the maximum output power can be 7.8mW and the device can still work at 100°C.
980nm InGaAs/GaAs separate confinement heterostructure (SCH) strained quantum well (QW) laser with non-absorbing facets is fabricated. The microchannel coolers is designed and fabricated with a five-layer thin oxygen-free copper plate structure. We report the operating characteristics of 980 nm high power semiconductor laser stacked arrays packaged by microchannel coolers. A highest CW output power of 200 W for 5-bar arrays is obtained.
980nm InGaAs/GaAs separate confinement heterostructure (SCH) single quantum well (SQW) laser is grown by MBE. Photoluminescence and X-ray double crystal diffraction of the epilayer demonstrate good optical and crystalline quality. A QCW output power of 64.1W is achieved for a cm bar, which is limited by the current source. No thermal rollover in the output power is observed. The threshold current is 18.6A at 15°C. The slope efficiency is 1.14W/A with a corresponding power efficiency of 31.7%.
One of the most important technological challenges in the manufacture of high power lasers is to determine device quality and reliability without damaging the device itself. The low-frequency electrical noise has shown potential as a sensitive non-destructive indicator of device quality and reliability. In this paper, the noise levels in semiconductor lasers (LDs) operating in both unconducting state (Svl) and conducting state (Sv2) are measured. From our investigation, the device reliability is associated with not only Sv1 but also Sv2, if one of them is higher, the device is usually reliable. When the noise is used to estimate device reliability, both Sv1 and Sv2 should be measured and considered.
In this paper, through the analysis and in consideration of the facts which influence on the ultimate output power of semiconductor laser. we report a novel 940nm semiconductor laser array structure with nonabsorbing facets to avoid the COMD on facets. The 940nm laser wafers are grown by MBE. The lasers were cleaved into cm bars. We have made a new design variant of laser array with nonabsorbing facets and coated high-and low-reflectivity coating (approx.95% and 5%). The emission wavelength of the laser arrays is 939nm. Continuous wave (CW) output power of 15 W has been achieved.
In this paper we report a 980 nm InGaAs/GaAs MQW semiconductor laser array. The epilayer structures are grown by MBE. We have fabricated broad areas lasers with a cavity length of 1000micron and a stripe width of 6micron and a stripe spacing of 100micron. The measurements are performed in quasi-continuous wave mode (QCW). The highest QCW output power of 12W for laser array with coated facets is achieved. The threshold current density is 400 A/cm2 at 15degree. The slope efficiency is 0.74W/A. The lasing spectrum is peaked at 979.4 nm with a FWHM of 3nm.
In this paper, through the analysis and in consideration of the facts which influence on the ultimate output power of semiconductor laser, we have designed a laser structure with gradient refraction index separate confinement single quantum well (GRIN-SCH-SQW) and have grown the laser structure by MBE. Moreover we have also fabricated array lasers by broad area structure. The lasers are cleaved into cm bars and coated with high- and low-reflectivity films (approx. 95% and 5%). The QCW output power of the array laser has reached 60 W (100 microsecond(s) , 500 Hz), the peak wavelength of the device is 806 approximately 810 nm.
In this letter we report a novel 980 nm semiconductor laser array structure with nonabsorbing facets to avoid the COMD on facets. The 980 nm laser wafers are grown by MBE. Using quantum-well intermixing, we have fabricated nonabsorbing mirrors on the laser array's facets to resist COMD. The quantum intermixing process involves the deposition of a thin film (200 nm) of sputtered SiO<SUB>2</SUB> and a subsequent high temperature anneal (680 - 760 degrees Celsius). The cm bars are cleaved to lengths of 1 mm and their rear and front nonabsorbing facets are coated respectively with high and low reflectivity dielectric film by electron-beam. The devices are bonded p-side up onto copper heatsinks using indium solder and mounted on a water-cooled stage which is held at 18 degrees Celsius for all experiments. The emission wavelength of the laser arrays is 980 nm. Continuous wave (CW) output power of 8 W has been achieved.
A detailed operating characteristics of InGaAsP/GaAs separate confinement heterostructure single-quantum-well wide-stripe lasers emitting at 808 nm grown by liquid phase epitaxy is reported. The temperature dependences of the lasing wavelength (lambda) , the threshold current density J<SUB>th</SUB> and differential quantum efficiency (eta) <SUB>d</SUB> are studied. The effects of the cavity length L on the threshold current density J<SUB>th</SUB> and the differential quantum efficiency (eta) <SUB>d</SUB> are studied. The threshold current density J<SUB>th</SUB> increases with increasing temperature T. But the increase of J<SUB>th</SUB> with temperature T is slightly deviated from the exponential dependence. The data fitting of J<SUB>th</SUB> with between 10 degree(s)C and 40 degree(s)C demonstrates a record characteristic temperature T<SUB>0</SUB> of 218 K, indicating a minor influence of temperature on J<SUB>th</SUB>.
In this work, we report Al-free InGaAsP/GaAs separate confinement heterostructure single quantum well structures for lasers emitting at 808 nm are grown by enhanced liquid phase epitaxy. The highest continuous wave output power is 4 W for lasers with coated facts. The differential efficiency is 1.32 W/A. The record characteristic T<SUB>0</SUB> of the laser is estimated to be about 218 K between 10 degree(s)C and 40 degree(s)C from the temperature dependence of the threshold current density J<SUB>th</SUB>.
In this paper, we adopted GaAlAs/GaAs SCH single quantum well wafer, which is grown by MBE, to complete one centimeter monolithic laser arrays, and two array structures were carried out on purpose to obtain cw and quasi-sw laser output respectively. In the experiment, by means of twice photoetching and chemical etching methods were used to isolate active regions to prevent photons from passing from one to another and amplified spontaneous emission. Results were presented for arrays which reach a maximum cw output power of 7 W perfacet and 50 W (200 microsecond(s) , 50 Hz) quasi-sw output, with lasing wavelength 806 - 810 nm.
In this paper we will report GaAlAs/GaAs gradient refraction index separate confinement quantum wells structures by MOCVD growth and its optical properties. The sample were characterized by high-resolution photoluminescence measurements. For 8 nm single quantum well, the excitation luminescence spectra at 10 K are characterized by transitions which has a linewidth (FWHM) of 6.2 nm and large intensity, indicating abrupt GaAlAs/GaAs interface. The shift of X(e-hh) peak position versus the excitation level are also observed. The results of PL measurement show that sample quality has met the requirement of design and proven to be satisfactory.
GaAlAs/GaAs hetero-epitaxial thin films are prepared by liquid phase epitaxy (LPE) technique. Structural characteristic of the film was Studied by X-ray double crystal rocking curve method. We have measured the rocking curve of (400) reflection and observed the interference fringes. Computer simulation of the experimental curves have been performed with kinematical and dynamical diffraction theory, respectively. We discussed the reason for the appearance of the interference fringe, and calculated structure parameters. The results obtained using dynamical theory is closer to the actual growth parameters.
A high power superluminescent diode (SLD) is developed on the basis of the terraced substrate inner laser diodes. The device is made of the characteristic of LPE of crystal on the non- planar substrate. The device's output power before assembled is 7 mW under operating current 150 mA. The wavelength is about 860 nm. The half width of the spectrum is 23 nm. The device is coupled with fiber (NA equals 0.23, D equals 50 micrometer). The coupling efficiency is about 30%. The pigtail fiber maximum output power is 2 mW.
In this paper we introduce a method of measuring thin layer thickness using a sandwich structure of the In<SUB>0.43</SUB>Ga<SUB>0.57</SUB>As<SUB>0.15</SUB>P<SUB>0.85</SUB>/In<SUB>0.13</SUB>Ga<SUB>0.87</SUB>As<SUB>0.75</SUB>P<SUB>0.25</SUB>/In<SUB>0.43</SUB>Ga<SUB>0.57</SUB>As<SUB>0.15</SUB>P<SUB>0.85</SUB> DH with the interference fringes in rocking curve by x-ray double-crystal diffraction.
The measuring conditions of the thickness of thin films with grazing incident x-ray is explained, and interferential principle and method to measure the thickness of thin films by grazing incident x-ray are discussed and analyzed in the paper. The periodic thickness of the multilayer optical thin films is measured with double-crystal diffractometer at a very small grazing incident angle, the result is satisfactory and measured values is in good agreement with designed values.
This paper summarizes the technical characteristics and performance of our newly purchased VG V80H MBE system. Our research work on thin film semiconductor laser materials growth on this system has also been presented here, with some discussion on beam flux stability and growth uniformity et al.
We have successfully designed and prepared gain-guided high power 1 .3- 1 .55i m leaky waveguide (LWG) laser
diodes. taking into account their loss mechanisms such as Auger electron non-radiative recombination, carrier leakage
over the heterobarrier, and inter-valence-band absorption etc. This is the first time to incorporate the leaky waveguide
structure into the quaternary 111-V compounds in order to obtain in long wavelength region high power laser diodes for
advanced manufacturing and metrology. In this work we have shown that the incorporation of the leaky waveguide
structure into the material system would reduce the threshold current density and alleviate the loss mechanisms. This
would result in a reduction in lasing threshold current and an improvement in the temperature sensitivity.
It was grown by a unique liquid phase epitaxy (LPE) and was modified by growing an intrinsic InGaASP
waveguiding layer which replaced its n-type counterpart as in usual large optical cavity devices and provided a higher
temperature stability than that of conventional DH lasers. Using the LWG structure, we have obtained 1 .55 i m laser
diodes with threshold currents comparable to common lasers ( th 2.7 KA/cm2) but with the characteristic
temperature T0 near to those of GaAs-AlGaAs lasers (140K).Especially, we have attained the peak output powers up
to higher than 2W per facet in pulsed operation at room temperature.
A gain-guided high-power 1.55 micrometers large optical cavity (LOC) laser structure was successfully prepared based on considerations of laser loss mechanisms such as auger electron recombination, carrier leakage over the heterobarrier, inter-valence-band absorption and so forth. The structure was grown by a unique liquid phase epitaxy (LPE) and was modified by growing an intrinsic InGaAsP waveguiding layer which replaced its n-type counterpart as in usual LOC devices and provided a higher temperature stability than that of conventional DH lasers. Using the LOC structure, we have obtained 1.55 micrometers laser diodes with threshold currents comparable to commercial lasers (J<SUB>th</SUB> < 2.7 KA/cm<SUP>2</SUP>) but with the characteristic temperature T<SUB>o</SUB> near to those of GaAs-AlGaAs lasers (140 K). Especially, we have attained the peak output power up to higher than 2 W per facet in pulsed operation at room temperature.