Pb1-xSnxSe/Pb1-x-yEuySnxSe corrugated diode lasers

The design, fabrication, and testing of distributed Bragg reflector (DBR), distributed feedback (DFB), and grating coupled emission (GCE) Pb_1-xSn_xSe/Pb_1-x-yEu_ySn _xSe double heterostructure stripe geometry molecular-beam-epitaxy (MBE) grown diode lasers are discussed. The DBR and DFB lasers are the first Pb-salt corrugated lasers to operate in CW (continuous) mode at temperatures above that of liquid nitrogen. For the GCE lasers, a narrow far field distribution of ~5° was obtained for the first time     

Type-II interband cascade lasers in the 4.3-4.7-/spl mu/m wavelength region

Operation of type-II interband cascade lasers in the 4.3-4.7-/spl mu/m wavelength region has been demonstrated at temperatures up to 240 K in pulsed mode. These lasers fabricated with 150-/spl mu/m-wide mesa stripes operated in continuous-wave (CW) mode up to a maximum temperature of 110 K, with an output power exceeding 30 mW/f and a threshold current density of about 41 A/cm/sup 2/ at 90 K. The maximum CW operation temperature of 110 K is largely limited by the high specific thermal resistance of the 150-/spl mu/m-wide broad area lasers. A 20-/spl mu/m-wide mesa stripe laser was able to operate in CW mode at higher temperatures up to 125 K as a result of the reduced specific thermal resistance of a smaller device.     

Pb1-xSnxTe/PbTe1-ySeylattice-matched buried heterostructure lasers with CW Single mode output

The first successful realization of buried heterostructure diode lasers in the PbSnTe/PbTeSe system is reported. This has resulted in routine cw operation above 80 K with threshold currents as low as 60 mA in 5 µm wide stripe lasers. CW operation has been achieved to 120K. In addition, these lasers operate in the fundamental transverse mode up to as much as four times threshold.     

Improved CW operation of GaAs-based QC lasers: T/sub max/= 150 K

We present a substantial improvement in the CW performance of GaAs-based quantum cascade lasers with operation up to 150 K. This has been achieved through suitable changes in device processing of a well-characterized laser. The technology optimizes the current injection in the laser by reducing the size of the active stripe whilst maintaining a strong coupling of the optical mode to preserve low current densities. The reduction of total dissipated power is critical for these lasers to operate CW. At 77 K, the maximum CW optical power is 80 mW, threshold current is 470 mA, slope efficiency is 141 mW/A, and lasing wavelength /spl lambda//spl sim/10.3 /spl mu/m.     

Mesa-stripe Pb1-xSnxSe tunable diode lasers

A mesa-stripe configuration for diffused junction Pb1-xSnx- Se lasers has been developed. The new lasers exhibit substantially improved performance over nonstripe devices, including CW operating temperatures up to 118 K, overall tuning ranges as wide as 444 cm^-1, and single-mode tuning ranges typically 1-3 cm^-1for current tuning and as wide as 5.5 cm^-1for temperature tuning. Surface leakage currents are shown to have a major effect on the operating characteristics of these and other Pb-salt devices. Results provide evidence for high internal quantum efficiencies and indicate that free carrier absorption is an important factor limiting power output in Pb-salt lasers. Observations of spectral mode behavior as a function of bias current are consistent with Zee's gain saturation model.     

Pb_(1-x)Sn_xTe和Pb_(1-y)Sn_ySe激光晶体

本文报道了具有合适的载流子浓度,低位错密度和适当p-n结深度的Pb_(1_x)Sn_xTe 和Pb_(1_υ)Sn_υSe激光晶体。这种晶体是用水平无籽晶气相生长技术和适当控制生长条件直接得到的,用这两种晶体已经制成OW运转的可调谐二极管激光器。     

InAsSb/InAsSbP double-heterostructure lasers emitting at 3–4 µm: Part I

Previous publications concerned with the development and investigation of InAsSb/InAsSbP double heterostructure lasers emitting at 3–4 μm fabricated by liquid phase epitaxy are reviewed. In pulsed mode, the maximum operating temperature of the lasers is 203 K, the characteristic temperature is 35 K, and differential quantum efficiency is 20±5% at 77K. Mesa-stripe lasers with a 10-to 30-μm stripe width and a 200-to 500-μm cavity length can operate in CW mode up to 110 K. The total optical output power of more than 10 mW at λ=3.6 μm is obtained at T=82 K in CW mode. The output power per mode does not exceed 2 mW/facet. A single-mode lasing is achieved in the temperature range of 12–90 K. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 34, No. 11, 2000, pp. 1396–1403. Original Russian Text Copyright ? 2000 by Danilova, Imenkov, Sherstnev, Yakovlev.     

High temperature CW operation of 1.5 ?m InGaAsP/InP buffer-layer loaded planoconvex waveguide lasers

InGaAsP/InP buffer-layer loaded planoconvex waveguide lasers are reported. The CW threshold current at 20°C was 70 mA. The maximum CW operating temperature of 70°C was achieved. The characteristic temperature under CW operation was 51 K. Operation in fundamental transverse mode and single longitudinal mode up to 1.9 and 1.4 times the threshold current, respectively, was obtained.     

Distributed Bragg-reflector Pb1-xSnxTe/PbSeyTe1-ydiode lasers

Distributed Bragg-reflector (DBR) diode lasers were designed and fabricated from lattice-matched Pb1-xSnxTe/PbSeyTe1-ysingle heterostructures grown by liquid-phase epitaxy. These DBR lasers operated in a single longitudinal mode within a limited range of heat-sink temperatures, 8.5-38 K, with a threshold current density of ∼3 kA/cm²at 20 K. Single longitudinal mode operation was maintained up to more than three times the threshold current. Continuous tuning of the laser output frequency over a range of ∼6 cm^-1, near 775 cm^-1(12.9 μm), was acheived by varying the heat-sink temperature. The average tuning rate was 0.21 cm^-1/K, and it was much smaller than the rate for corresponding Fabry-Perot lasers, which was 2.3 cm^-1/K. The measured effective mode index of the DBR lasers agrees well with the calculated one.     

Resonant-phonon terahertz quantum-cascade laser operating at 2.1 THz (/spl lambda//spl sime/141 /spl mu/m)

The development of quantum-cascade lasers (QCLs) at 2.1 THz (/spl lambda//spl sime/141 /spl mu/m), which is the longest wavelength QCL to date without the assistance of magnetic fields, is reported. This laser uses a structure based on resonant-phonon depopulation, and a metal-metal waveguide to obtain high modal confinement with low waveguide losses. Lasing was observed up to a heatsink temperature of 72 K in pulsed mode and 40 K in continuous-wave (CW) mode, and 1.2 mW of power was obtained in CW mode at 17 K.     

Lead chalcogenide mid-infrared diode lasers fabricated byion-implantation

Ar⁺ implanted PbSe mid-infrared (MIR) lasers have been fabricated, characterized, and analyzed. For the first time, the operation of ion-implanted lead-salt mid-infrared diode lasers in continuous-wave (CW) mode at temperatures above 77 K was achieved. The maximum operating temperatures of 115 K in CW mode and 155 K in pulse mode were reached. These lasers have high output power, low linewidth, and small tuning rate, as well as comparatively low threshold currents. These promising properties demonstrated that ion-implanted MIR lasers are competitive candidates as tunable sources in the applications of high-resolution spectroscopy and trace-gas analysis     

High power and high efficiency operation of Al-freeInGaAs/GaInAsP/GaInP GRINSCH SQW lasers (λ≃0.98 μm)

High power and high quantum efficiency Al-free InGaAs/GaInAsP/GaInP GRINSCH SQW lasers emitting at 0.98 μm are reported. A CW output power as high as 580 mW and single lateral mode power up to 280 mW were achieved for the Al-free ridge waveguide lasers at room temperature. The lasers exhibited a high internal quantum efficiency of 99% and low internal waveguide loss of 3.2 cm^-1. A high characteristic temperature of 217 K and low threshold current density of 109 A/cm² were also obtained. The results are the best obtained for Al-free 0.98 μm pumping lasers     

InGaAsP/InP separated multiclad layer stripe geometry lasers emitting at 1.5 ?m

InGaAsP/InP separated multiclad layer stripe geometry lasers emitting at 1.5 ?m are reported. The CW threshold current at 25°C is only 82 mA and the maximum temperature where CW lasing is obtained is 65°C. The characteristic temperature of the pulsed threshold current is 60 K. The transverse mode is fundamental and the longitudinal mode is single up to 1.5 times the threshold under CW operation. A few samples operated for over 1000 h at 50°C under constant optical power operation of 5 mW/facet.     

Influence of KTP length on the performance intracavity frequencydoubled diode-pumped Nd:YVO4 lasers

We demonstrate an experimental study of the influence of potassium titanyl phosphate (KTP) length on the performance of intracavity frequency-doubled diode-pumped Nd:YVO₄ lasers operating in continuous-wave (CW) mode and passive Q-switch mode. Theoretical and experimental results show that the optimum KTP length for CW mode is determined by the nonlinear coupling and walkoff effect and the highest optical conversion efficiency in CW mode is nearly 30% with a 10-mm KTP. On the other hand, a 2-mm KTP crystal, which is sufficient for efficient internal second-harmonic generation in a passive Q-switch mode, yield the highest peak green power of 240-W     

Single heterostructure lasers of PbS1-xSexand Pb1-xSnxSe with wide tunability

Single-heterostructure diode lasers formed by compositional interdiffusion in PbS1-xSexand Pb1-xSnxSe and by liquid-phase-epitaxy (LPE) in Pb1-xSnxSe show Performance characteristics significantly better than those observed in conventional homostructure lasers. Higher operating temperatures were obtained for all compositions, with CW operation above 77 K being achieved for compositions corresponding to wavelengths from 4.1 to 12.7 μm. Single-ended, CW powers as high as 70 mW, corresponding toeta_{ext} = 44percent were observed in PbS1-xSexdevices.     

The mode competition,instability, and second harmonic generation in dual-frequency InGaAs/GaAs/InGaP lasers

InGaAs/GaAs/InGaP-based heterolasers with asymmetrically grown quantum wells of two types are developed. For the first time, dual-wavelength operation and second-harmonic generation are realized in these lasers over a wide range of injection currents: from 0.2 A in CW mode up to 10 A in injection with 200-ns-long pulses. Previously unknown special features of such a generation are experimentally revealed and interpreted in terms of the competition and coexistence of various short-and long-wavelength modes, including the “whispering-gallery” modes.     

Room-temperature continuous-wave operation of InAs quantum-wire laser on InP(001) substrate

A self-assembled quantum-wire laser structure was grown by solid-source molecular beam epitaxy in an InAlGaAs-InAlAs matrix on InP(001) substrate. Ridge-waveguide lasers were fabricated and demonstrated to operate at a heatsink temperature up to 330 K in continuous-wave (CW) mode. The emission wavelength of the lasers with 5 mm-long cavity was 1.713 /spl mu/m at room temperature in CW mode. The temperature stability of the devices was analysed and the characteristic temperature was found to be 47 K in the range of 220-320 K.     

2.0-/spl mu/m single-mode operation of InGaAs-InGaAsP distributed-feedback buried-heterostructure quantum-well lasers

Distributed-feedback (DFB) buried-heterostructure (BH) lasers with quantum-well active region emitting at 2.0 /spl mu/m have been fabricated and characterized. The lasers with four wells showed performance of practical use: threshold current as low as 15 mA for 600-/spl mu/m-long devices and CW single-mode output up to 5 mW at 2.03 /spl mu/m under operation current of 100 mA were observed. The current- and temperature-tuning rates of DFB mode wavelength are 0.004 nm/mA and 0.125 nm/K, respectively.     

Operating characteristics of single-quantum-well AlGaAs/GaAshigh-power lasers

The operating characteristics of six types of graded-index separate confinement heterostructure single-quantum-well wide-stripe lasers grown by metalorganic chemical vapor deposition are reported. The lasers exhibited intrinsic mode losses as low as 3 cm^-1 and internal quantum efficiencies near unity. Measured differential gain coefficients range from 3.7 to 6.5 cm/A, and extrapolated transparency current densities range from 54 to 145 A/cm². These wide-stripe lasers are typically multilongitudinal mode and exhibit narrowing of the gain envelope and lateral far-field pattern as the cavity length increases. The high value of T₀(>200 K) at long cavity lengths in conjunction with the low current density permits junction-side-up operation to CW optical powers of 0.5-0.7 W/facet, at which level catastrophic facet damage occurs on the uncoated devices. A maximum power conversion efficiency of 57% was measured on the laser structure exhibiting the lowest threshold current     

FM mode-locked high-pressure CW RF-excited CO2 waveguidelaser

The authors report the results from a study of a FM mode-locked continuous-wave (CW) RF-excited CO₂ waveguide laser operated at 0.25-2 atm gas pressures. It is shown that electrooptic FM modulations can be efficiently used to mode lock a CW CO₂ laser. The combination of a high gas pressure and a high modulation frequency makes it possible to generate pulses which are substantially shorter than those previously reported for CW mode-locked CO₂ lasers. A theoretical approach is used for simulation of the FM mode-locked laser. The experimental pulses of a few hundred picoseconds FWHM are considerably shorter than previously reported for CW mode-locked CO₂ lasers. The experimental results are compared with the results of numerical calculations using a frequency domain simulation model