Theoretical and experimental study of threshold characteristics in InGaAsP/InP DH lasers

Threshold characteristics of stripe-geometry InGaAsP/InP double-heterostructure injection lasers have been analytically derived as a function of active layer thickness and stripe width. The effects of stripe width, refractive index in the active layer, diffusion of injected carriers, carrier lifetime, absorption loss in the cladding layer, gain coefficient, and cavity length on the optimum thickness of the active layer which gives minimum threshold or on threshold current density were studied. These lasers were fabricated on     

Oxide defined TJS lasers in InGaAsP/InP DH structures

Transverse junction stripe lasers in the InGaAsP-InP systems have been fabricated by Zn diffusion through oxide windows into DH structures of InGaAsP/InP with all epitaxial layers n-type. The quaternary layer composition is such that room temperature laser emission is at 1.18 μm. TJS laser mode behavior with accompanying single longitudinal mode operation and kink-free light-output characteristics are seen at 77 K. As the temperature is increased, this behavior persists up to about 130 K, when parallel electron injection through the p-n junction in the InP layers becomes so large that, in parallel with the TJS laser filament, a normally operating DH laser filament starts operating. At higher temperatures only the latter is seen to operate.     

Influences of interfacial recombination on oscillation characteristics of InGaAsP/InP DH lasers

This paper presents the influences of interfacial recombination on the oscillation characteristics of InGaAsP/InP DH lasers. The effects of interfacial recombination at the two InP-InGaAsP interfaces, and a theoretical study of the oscillation characteristics such as threshold current density and differential quantum efficiency are discussed and compared with experimental results. The effects of interfacial recombination on the temperature dependence of threshold current are also examined.     

Aging characteristics of InGaAsP/InP DFB lasers

Aging tests of InGaAsP/InP DFB lasers with a constant light output of 5 mW/facet and ambient temperatures 25°C and 40°C have been carried out. Up to the present, with an aging time of more than 2000 h for six lasers, appreciable degradations have been observed in their driving currents and spectra. This indicates that the corrugation grating near the active region has little influence on short-term reliability of DFB lasers.     

Etched-coupled-cavity InGaAsP/InP lasers

A new structure for coupled-cavity lasers operating at 1.25 ?m wavelength is presented. Using chemical etching, we made a three-cavity laser from an index-guided channelled-substrate Fabry-Perot laser. It oscillates in a single longitudinal mode with a side-mode suppression ratio of 200:1 in the pumping current range of 120 mA to 220 mA. The same mode was maintained at a fixed current of 160 mA as the heat-sink temperature was varied from 9°C to 45°C. The advantages of this laser over other coupled-cavity lasers are the simplicity of fabrication, the accuracy of cavity length control, and the possibility of incorporating short-etalon sections in the coupled cavities.     

InGaAsP/InP dual wavelength lasers

The first successful dual wavelength lasers emitting at 1.2 ?m and 1.3 ?m wavelengths are described. The lasers operated up to 0°C.     

InGaAsP/InP双异质结发光管中的深能级

本文用DLTS谱仪研究了SiO2限制的InGaAsP/InP双异质结发光管中的深能级。结果表明:只有在p-n结位于p-InP/n-InGaAsP界面处的个别器件中,有△E=0.24eV的多子陷阱。     

InGaAsP/InP BH lasers on p-type InP substrates

A 1.55 ?m InGaAsP/InP BH laser is achieved on a p-type InP substrate resulting in a simple fabrication process. A threshold current as low as 40 mA under CW operation and a pulsed power rating of several hundred mW at 8 A peak current are achieved in buried-heterostructure lasers.     

Properties of wide-mesastripe InGaAsP/InP lasers

Wide-mesastripe InGaAsP/InP heterostructure lasers emitting at 1.3–1.5 µm were grown by metal-organic chemical vapor deposition (MOCVD). Radiation-power-current and spectral characteristics of the lasers have been studied in pulsed and continuous wave (cw) operation in the temperature range of 10–60°C. The temperature of the active region of the diode laser is higher by 30–60°C than that of the copper heatsink upon saturation of the cw output power. The temperature dependence of the differential quantum efficiency strongly affects the cw output power. Output powers of 3 and 2.6 W are achieved in mesastripe lasers in cw operation, and 9 and 6.5 W in pulsed operation, at wavelengths of 1.3 and 1.5 µm, respectively.     

Low-threshold-current distributed-feedback InGaAsP/InP CW lasers

Distributed-feedback buried-heterostructure InGaAsP/InP lasers with room temperature CW threshold current as low as 50 mA, corresponding to a current density of 2.3 kA/cm2, are presented. CW operation in the temperature range from ?20°C to 58°C was confirmed.     

InGaAsP/InP distributed feedback buried heterostructure lasers with both facets cleaved structure

Feasibilities of InGaAsP/InP distributed feedback buried heterostructure lasers in the 1.3 and 1.5 μm wavelength regions with two cleaved facets are shown. Theoretical and experimental examinations show that the kL values ranging between 1 and 2 are sufficient for high-performance operation with the stable single longitudinal mode in a temperature range wider than 100 degrees. Distribution of lasing characteristics is investigated for 140 randomly chosen LD's from two wafers. Approximately 65 percent of the devices are found to be operable in the single longitudinal mode. A CW single longitudinal mode operation power of 20 mW at 25°C for a 1.5 μm device, and that of 40 mW (60 mW with AR coating) at 25°C for a 1.3 μm device with low threshold current are achieved. These characteristics are attained by both first- and second-order grating devices fabricated by the PH3addition LPE technique. The results of the aging test at 70°C and 110 mA in the automatic current control condition are also presented.     

Facet oxidation of InGaAsP/InP and InGaAs/InP lasers

The facet oxidation of InGaAsP/InP and InGaAs/InP lasers is investigated after aging under high constant optical output power or high current stress. Facet oxidation in InGaAsP/InP lasers is negligibly small under several thousand hours of practical operation. The thickness of oxide film increases in proportion to optical output power and logarithm of aging time. The growth rate of facet oxide film weakly depends on the junction temperature and the activation energy is estimated to be 0.07 eV within a experimental range between 25 and 150°C. The facet of InGaAs/InP lasers are oxidized more easily than that of InGaAsP/InP lasers but are about two orders of magnitude more stable against oxidation than that of AlGaAs/GaAs lasers.     

Narrow spectral linewidth characteristics of monolithic integrated-passive-cavity InGaAsP/InP semiconductor lasers

The spectral linewidth of 1.3 ?m monolithic integrated-passive-cavity (IPC) semiconductor laser is measured by a delayed self-heterodyne technique. It is found that the line-width is narrowed when longitudinal submode is suppressed. The narrowest linewidth obtained so far is 900 kHz at 6 mW output power.     

Temperature dependence of bistable InGaAsP/InP lasers

An increase of hysteresis current width in bistable lasers with two or three sections was observed at higher temperatures. A rate equation analysis was performed where both carrier density dependence on lifetime and the bleaching of saturable absorption by the spontaneous emission were taken into account. We show that the increased loss of injected carriers due to Auger recombination process causes the increase in the hysteresis width. A small-signal stability analysis for the switch-off point revealed that increased coupling between carriers in the gain and absorption regions, through the absorption of superradiant emission, has the effect of raising the switch-off point to higher current levels. It was shown experimentally that, without changing the temperature, the current hysteresis width can be controlled by adjusting the current distribution in three sections.     

Tuning characteristics of optical amplification in 1.5 ?m InGaAsP/InP lasers

The bias current dependence of tuning wavelength in an optical amplifier is investigated in detail. Tuning wavelength decreases below threshold at the rate of ?0.36 ?/mA, mainly due to the change of carrier density, and increases at the rate of 0.11 A/mA above threshold due to the thermal effect.     

Stripe geometry InP/InGaAsP lasers fabricated with deuteron bombardment

Stripe geometry gain-guided InP/InGaAsP lasers have reproducibly been fabricated with deuteron bombardment. Good electrical isolation was observed in 250-µm-long laser chips, and CW thresholds as low as 105 mA have been achieved.     

GaInAsP/InP DH lasers with a chemically etched facet

We describe a new configuration and novel fabrication method for GaInAsP/InP DH lasers in which one of the facet mirrors is chemically etched and the other one is formed by cleaving. The etched facet is fabricated monolithically by wet chemical etching in a solution of HCl:CH3COOH:H2O2= (1:2:1). Broad-area contact lasers of this type operating at room temperature at a wavelength ofsim 1.3 mum have been demonstrated.     

Hybrid LPE/MBE-grown InGaAsP/InP DFB lasers

InGaAsP/InP distributed-feedback (DFB) lasers operating at 1.5 ?m have been successfully fabricated by a hybrid growth technique of liquid phase epitaxy (LPE) and molecular beam epitaxy (MBE). A threshold current of 180 mA at 23°C and single-longitudinal-mode operation have been obtained.