Performance characteristics of high-brightness, CW, diode laser arrays

Recently developed, high-brightness diode laser arrays have been tested at 50°C at output powers of 0.5 W CW and 1.0W CW from 100?m- and 200?m-wide active regions, respectively. The extrapolated lifetimes at room temperature exceed 40000 h. The maximum CW power output prior to catastrophic degradation of the facets is 2.0 W for the 100?m device and greater than 3 W for the 200?m-aperture device.     

High power, 8.5 W CW, visible laser diodes

Visible laser diodes have been fabricated from AlGaInP operating at approximately 680 nm to high output powers. Broad area lasers with 100 mu m wide emitting apertures operate to greater than 1 W CW with a different efficiency of 38%. The threshold current densities of the material have been measured to be as low as 350 A/cm/sup 2/ for lasers with 30% mirror reflectivities. Monolithic bars 8 mm long with 50 mu m emitting apertures periodically spaced on 500 mu m centres have been fabricated which operate to 8.5 W CW.<>     

MOVPE growth of AlGaAs/GaInP diode lasers

GaAs-based diode lasers for emission wavelengths between 800 nm and 1060 nm with AlGaAs-cladding and GaInP-waveguide layers were grown by MOVPE. For wavelengths above 940 nm broad area devices with InGaAs QWs show state-of-the-art threshold current densities. Ridge-waveguide lasers fabricated by selective etching achieve 200 mW CW monomode output powers. (In)GaAsP QW-based diode lasers with an emitting wavelengths around 800 nm suffer from problems at the upper GaInP/AlGaAs interface. Asymmetric structures with a lower AlGaAs/GaInP and an upper AlGaAs/AlGaAs waveguide not only avoid this interface but also offer better carrier confinement. Such structures show very high slope efficiencies and a high T₀. Maximum output powers of 7 W CW are obtained from 4 mm long devices.     

Reliability of 1.3 ?m V-grooved inner-stripe laser diodes under high-power operation

Aging tests of 1.3 ?m laser diodes were performed under extremely high power levels up to 85% of the maximum CW output powers. We have verified high reliability under high power levels as high as 75% of the maximum CW output powers at room temperature. The median lifetime is estimated to be 7×104 h at 75% of the maximum CW output power.     

Improved Ti:sapphire laser performance with new high figure ofmerit crystals

The continuous-wave (CW) laser performance of Ti:Al₂O ₃ crystals with high figure of merit is described. Using a 0.1% Ti:Al₂O₃ crystal (FOM=1000), output powers of 3.5 W at 800 nm are obtained, pumping with a 9.6 W argon ion laser operating multiline. Continuous tunability of the CW Ti:Al₂O ₃ laser extending from 665 to 1070 nm is also demonstrated for a 5 W pump power     

230W C-band GaN-FET power amplifier

A C-band high-power amplifier with two GaN-based FET chips exhibits record output powers under continuous-wave (CW) and pulsed operation conditions. At 5.0 GHz, the developed GaN-FET amplifier delivers a CW 208 W output power with 11.9 dB linear gain and 34% power-added efficiency. It also shows a pulsed 232 W output power with 8.3 dB linear gain.     

100 W C-band single-chip GaN FET power amplifier

A single-chip GaN-FET amplifier exhibits record output powers of C-band solid-state amplifiers under continuous-wave (CW) and pulsed operation conditions. At 5.0 GHz, the developed GaN-FET amplifier with 24 mm gate periphery delivered a CW 100 W output power with 12.9 dB linear gain and 31% power-added efficiency and a pulsed 155 W output power with 13.0 dB linear gain.     

Short wavelength (/spl lambda//spl sim/4.3 /spl mu/m) high-performance continuous-wave quantum-cascade lasers

We report continuous-wave (CW) operation of a 4.3-/spl mu/m quantum-cascade laser from 80 K to 313 K. For a high-reflectivity-coated 11-/spl mu/m-wide and 4-mm-long laser, CW output powers of 1.34 W at 80 K and 26 mW at 313 K are achieved. At 298 K, the CW threshold current density of 1.5 kA/cm/sup 2/ is observed with a CW output power of 166 mW and maximum wall-plug efficiency of 1.47%. The CW emission wavelength varies from 4.15 /spl mu/m at 80 K to 4.34 /spl mu/m at 298 K, corresponding to a temperature-tuning rate of 0.87 nm/K. The beam full-width at half-maximum values for the parallel and the perpendicular far-field patterns are 26/spl deg/ and 49/spl deg/ in CW mode, respectively.     

High-power 980 nm quantum dot broad area lasers

High-power quantum dot broad area lasers emitting at 980 nm are presented. Continuous-wave output powers of 4.3 W from a 50 /spl mu/m stripe width laser and of 6.3 W from a 100 /spl mu/m stripe width laser were achieved at 15/spl deg/C     

A GaAs distributed IMPATT diode amplifier

Stable microwave amplification has been obtained in GaAs distributed IMPATT (DIMPATT) diodes by the use of shorter than resonant length devices and appropriate input/output port terminations. CW output powers of 2 W were achieved at 9.5 GHz with 10-dB gain.     

High-Power Continuous-Wave Single-Longitudinal-Mode Operation of an Optically Pumped DFB Laser at $lambda sim 3.64~ mu$m

High-power continuous-wave (CW) single-longitudinal-mode emission at 3.64 mum is obtained from an optically pumped distributed-feedback (DFB) laser. The Bragg stopband and two degenerate DFB modes are observed at certain pump powers. The laser incorporates 14 InAs-InGaSb-InAs type-II quantum wells imbedded in an InGaAsSb waveguide. The index-coupled 1-D grating is fabricated in the top clad using interference lithography and plasma etching. A 110-mum-wide stripe from a 1.9-mum CW laser provides both optical pumping and gain guiding. Record high output power of more than 560 mW per side is obtained at 80 K. The wavelength is tunable over a 6.8-nm range by varying the pump power from 1 to 8.1 W.     

Optimization of GaAsP/AlGaAs-based QW laser structures for high power 800 nm operation

We present a detailed study of the MOVPE growth of 800 nm diode laser structures based on the combination of a GaAsP quantum well with well-established AlGaAs waveguide structures. By optimizing the strain and thickness of the quantum well highly-reliable diode lasers with low threshold current and high efficiency were demonstrated. 100 μm aperture “broad area” devices mounted epi-side up achieve a CW output power of 8.9 W with a wall-plug efficiency of 50%. These output powers represent record values for diode lasers in this wavelength range. Reliability measurements at 1.5 W and 50°C ambient temperature suggest lifetimes >10 000 h.     

Mid-infrared type-II interband cascade lasers

Interband cascade (IC) lasers that utilize optical transitions between the conduction and valence bands in a staircase of Sb-based type-II quantum wells (QWs) represent a new class of mid-IR diode lasers. By combining the advantages of quantum cascade lasers and type-II QW interband lasers, type-II IC lasers show promise of operating in continuous-wave (CW) mode up to room temperature with high output powers. Significant advances toward such high performance have been reported in terms of record-high differential external quantum efficiency (DEQE>600%), peak output power (~6 W/facet at 80 K), CW power conversion efficiency (>16% at 80 K), and room-temperature operation under pulsed conditions. Here, we will review the progress made in the past few years and discuss the issues encountered during the development. Also, the current status of type-II IC lasers and the remaining challenges will be discussed     

High-power output over 200 mW of 1.3 µm GaInAsP VIPS lasers

Maximum CW output power was investigated in GaInAsP 1.3μm V-grooved inner stripe on P-substrate (VIPS) lasers considering both cavity length and facet reflectivity. Long-cavity lasers show a strong dependence of maximum output power on front reflectivity. A CW light output over 200 mW was obtained at room temperature using a 700 μm long cavity laser with 5 and 98 percent reflectivity of the front and rear facets, respectively. The fundamental transverse mode operation was confirmed up to 170 mW. A coupled power over 110 mW into a single-mode fiber was achieved with a coupling efficiency of 58 percent. We have verified the high reliability under high power levels, as high as 75 percent of the maximum CW output powers at room temperature.     

Tapered diode lasers at 976 nm with 8 W nearly diffraction limited output power

High-efficiency tapered diode lasers with ridge-waveguide structure emitting at 976 nm have been realised. High wall-plug efficiencies of more than 57% result in output powers of more than 12 W for a single emitter with 3.5 mm resonator length. A nearly diffraction limited behaviour has been demonstrated up to 8.3 W CW.     

Efficient high power operation of erbium 3 μm fibre laserdiode-pumped at 975 nm

Efficient CW operation of a 2.71 μm Er,Pr:ZBLAN double-clad fibre laser pumped with a single diode laser operating at a wavelength of 975 nm is described. A maximum output power of 0.5 W and a slope efficiency of 25% (with respect to the launched pump power) were obtained. Threshold pump powers of <200 mW launched were measured and consistent relaxation oscillations in the output from the fibre laser indicate the presence of a saturable absorption mechanism     

Low-threshold continuous-wave 1.5-/spl mu/m GaInNAsSb lasers grown on GaAs

We present the first continuous-wave (CW) edge-emitting lasers at 1.5 /spl mu/m grown on GaAs by molecular beam epitaxy (MBE). These single quantum well (QW) devices show dramatic improvement in all areas of device performance as compared to previous reports. CW output powers as high as 140 mW (both facets) were obtained from 20 /spl mu/m /spl times/ 2450 /spl mu/m ridge-waveguide lasers possessing a threshold current density of 1.06 kA/cm/sup 2/, external quantum efficiency of 31%, and characteristic temperature T/sub 0/ of 139 K from 10/spl deg/C-60/spl deg/C. The lasing wavelength shifted 0.58 nm/K, resulting in CW laser action at 1.52 /spl mu/m at 70/spl deg/C. This is the first report of CW GaAs-based laser operation beyond 1.5 /spl mu/m. Evidence of Auger recombination and intervalence band absorption was found over the range of operation and prevented CW operation above 70/spl deg/C. Maximum CW output power was limited by insufficient thermal heatsinking; however, devices with a highly reflective (HR) coating applied to one facet produced 707 mW of pulsed output power limited by the laser driver. Similar CW output powers are expected with more sophisticated packaging and further optimization of the gain region. It is expected that such lasers will find application in next-generation optical networks as pump lasers for Raman amplifiers or doped fiber amplifiers, and could displace InP-based lasers for applications from 1.2 to 1.6 /spl mu/m.     

0.6 W CW GaInNAs vertical external-cavity surface emitting laser operating at 1.32 /spl mu/m

What is believed to be the first high-power vertical external cavity surface emitting laser (VECSEL) operating at 1.3 /spl mu/m is reported. CW output powers >0.6 W were achieved using a diode-pumped GaInNAs VECSEL structure capillary-bonded to a single-crystal diamond heatspreader.     

8.1W全固态准连续红光Nd∶YAG激光器

报道了利用Ⅱ类临界相位匹配的KTP晶体(相位匹配角选为θ=599°,=0°)对Nd∶YAG在13μm附近的振荡进行腔内倍频,产生高功率准连续红光激光的实验结果。激光器使用了一个连续运转的高功率激光二极管(LD)侧面抽运组件(组件内由30个20W的二极管阵列呈三角形阵列分布抽运一根Nd∶YAG圆棒),使用声光调Q技术实现高重复频率输出,并选用了平凹直腔的腔体结构。对该激光器的基频(13μm波长)调Q和倍频红光的功率输出特性及光谱特性进行了研究。在LD抽运功率453W时产生了最大输出功率81W的准连续红光激光,测量了此时的M2值并给出了光强分布图。     

Broadband 60-W HF linear amplifier

The design, construction and performance of a solid-state untuned 2-30 MHz amplifier is described. Operation is from 28 V dc. Overall CW efficiency is greater than 47 percent at 60-w unfiltered output. Amplifier efficiency for two-tone 60-W PEP output is greater than 31 percent. two-tone linearity over the frequency range is -30 dB or better at output powers from 5-60 W. Broadband transmission-line transformers wound on ferrite toroids are used throughout for impedance matching. Hybrids of similar construction are used for output-power adding.