In order to effectively reduce the surface state density of GaAs and obtain a stable high-performance passivation film, the GaAs surface was passivated by using the solution of octadecanethiol in different solvents. The effects of solvent polarity on passivated GaAs surface by octadecyl mercaptan solution were researched by X-ray diffractometry, photoluminescence and atomic force microscopy. The XPS test shows that the methanol compared to ethanol and isopropanol solvents, the surface of the GaAs after passivation has less oxide content, the As-S bond increases, and the density of octadecanethiol molecules attached to the surface increases. The PL measurement shows that the PL intensity of GaAs surface is highest by octadecanethiol methanol solution passivation, and it is 1.65 times higher than non-passivated. The surface stability test shows that the photoluminescence intensity of passivated GaAs surface do not deteriorate significantly after several days in air (PL intensity decreased by 22.1% within 30 days), which indicates that the self-assembled passivation layer of passivated GaAs surface has good stability.
In order to improve the thermal characteristics of single-chip semiconductor lasers and increase the output power of the device, a new type of vertical packaging structure of heat sink is proposed and analyzed. The heat sink retains the advantages of simplicity and being easy to apply, and the performance of heat dissipation has been improved obviously. The new heat sink structure is believed to be more suitable for packaging of the high-power semiconductor laser chips by heat conduction. Finite-element thermal analysis was used to simulate the thermal field distribution and thermal vector distribution in the conventional structure and the new structure. The simulation results show that the thermal resistance of the conventional structure is 2.0 K/W and the thermal resistance of the new heat sink is less than 1.6 K/W. The theoretical calculation results show that the output power of the packaged laser by new heat sinks can be significantly improved.
We designed and manufactured all optical fiber CTD to monitor ocean based on the sensitive characteristics about
optical fiber grating. A series of works have done, including the calibration work for sensor in laboratory, simulated
experiment outside and the local test of ocean parameter. The results we got show that the precision of temperature is
0.01℃ and of pressure is better than 0.1%, both of them overtake the secondary standard of GB/T23246-2009, moreover,
close to the primary standard, and of salinity in laboratory has reached 708 pm/1% closely to the secondary standard. It is
satisfied with the ocean monitoring requirements.
A novel fabrication method and process of Au(80wt.%)-Sn(20wt.%) eutectic alloys solder with excellent thermal,
electrical and mechanical properties and relatively low melting and reflow temperature was presented, the characteristic
of gold-tin alloy solder and the key technique to realize highly reliable bonding were discussed.
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 2×0.5mm2 and a satisfactory farfield (θ⊥) output property is also achieved with θ⊥ of 31o.
AlGaAs/GaAs material diode lasers grown by MOCVD using TBA as the group-V source and N2 as the carrier gas, was reported. Lasing has been successfully achieved with a low threshold current density of 506 A/cm2.
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%.
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.
The multiple layers quantum dots structure was grown by MBE technology. The temperature dependence of the modal gain of quantum dots was investigated by using the single pass amplified spontaneous emission method. The incorporation of extra layers of quantum dots didn't lead to an increase of the modal loss, inferring that the free carrier absorption in the doped cladding layers might dominate the loss mechanism. The peak modal gain exhibited an increase with temperature in the region of 140K to 200K, presumably due to the non-equilibrium distribution of carriers among the quantum dots.
Lasers based on InGaAs/(Ga,Al)As stacked QDs layers are fabricated. The performance of the quantum dots laser is dependent on the detailed design of the active region. The threshold current density is greatly decreased by the use of multiple-layer quantum dots, coupled dots layers, or barriers with wide band gap. An average threshold current density of about 20A/cm2 is achieved for the laser with the width of 15micron.
Silicon-based photonic wire waveguide was designed. The waveguide was consisted of a sandwiched structure with a nanocrystalline silicon film embedded between two low index silicon oxide films. The conformal transformation method was used in the simulation to obtain the basic coupling characteristics. The results showed that the coupling coefficient was strongly dependent on the gap spacing and the radius of the ring waveguide. A coupling efficiency of 10% could be obtained when the gap spacing was about 0.3 micrometers .
The farfield characteristics of a InGaAs/GaAs quantum dots laser was investigated. It was found that the farfield picture on the screen in front of the laser was composed of two straight lines due to the side modes of the junction. And the straight lines consisted of three bright spots, which we believe were presumably originated from the feedback of the substrate and the capping layer.
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 SiO2 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.
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 T0 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 Jth.
It was observed that a twin-lobe like farfield appeared more obviously with larger stripe width of BA LD, also with increasing injected current, due to much more complicated lateral modes. As a consequence, a single-lobed farfield output of 2.0 W has been realized with BA InGaAsP/GaAs SCH SQW lasers (stripe width 150 um).
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.
By using a recently modified LPE technique, extremely uniform InGaAsP/GaAs SCH SQW structure materials could be grown reproducibly. Single stripe lasers with 150 um emitting aperture generate 4.0 W in CW by improvement of waveguiding parameters and ohmic contact process.
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 Jth and differential quantum efficiency (eta) d are studied. The effects of the cavity length L on the threshold current density Jth and the differential quantum efficiency (eta) d are studied. The threshold current density Jth increases with increasing temperature T. But the increase of Jth with temperature T is slightly deviated from the exponential dependence. The data fitting of Jth with between 10 degree(s)C and 40 degree(s)C demonstrates a record characteristic temperature T0 of 218 K, indicating a minor influence of temperature on Jth.
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.
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.