We report the observation of the emission of solitons from a semiconductor circular ridge waveguide ring laser with a Y-junction coupler. The light-current (L-I) characteristics of the soliton emission through the nonwaveguide region, which refers to the photovoltaic solitons, has a low threshold value and a high quantum efficiency compare to the emission from the Y-junction coupler, and the spectrum of the soliton emission is similar to that of a linear strip laser with multimode emission. The feedback light from the end facet of the Y-junction coupling section continuously enhances the excitation of the photovoltaic solitons through the nonwaveguide region until the lasing condition is reached. It is suggested that the circular ring laser can be an alternative channel to light wave control in integrated optoelectronic system.

An angle-dependent surface photovoltage spectroscopy ͑SPS͒ study has been performed at room temperature on a GaAs/GaAlAs-based vertical-cavity-surface-emitting-laser ͑VCSEL͒ structure emitting at a wavelength near 850 nm. For comparison purposes, we have also measured the angle-dependent reflectance ͑R͒. The surface photovoltage spectra exhibit both the fundamental conduction to heavy-hole ͑1C-1H͒ excitonic transition and cavity mode plus additional interference features related to the properties of the mirror stacks, whereas in the R spectra only the cavity mode and interference features are clearly visible. The energy position of the excitonic feature is not dependent on the angle of incidence, in contrast to that of the cavity mode, whose angular dependence can be fitted with a simple model. This study demonstrates the considerable potential of angle-dependent SPS for the contactless and nondestructive characterization of VCSEL structures at room temperature.

Articles you may be interested inDifferential surface photovoltage spectroscopy characterization of a 1.3 μm InGaAlAs/InP vertical-cavity surfaceemitting laser structure An angle-dependent wavelength-modulated differential-photovoltage spectroscopy ͑DPVS͒ investigation has been performed at room temperature on a bare as-grown wafer of GaAs/ GaAlAs-based vertical-cavity surface-emitting laser ͑VCSEL͒ structure, designed for emitting at a wavelength near 850 nm. The differential-photovoltage ͑DPV͒ spectra exhibit both the fundamental conduction to heavy-hole excitonic transition and cavity mode plus an interference pattern related to the mirror stacks. By changing the angle of incidence in the DPV measurements the energy positions of the cavity mode and distributed Bragg reflector features show a blueshift while the excitonic transition remains unchanged. The energies of the excitonic transition and cavity mode are accurately determined from the DPV spectra. The advantages of DPVS in relation to other methods of characterizing VCSEL structures, such as surface photovoltage, photoreflectance, photocurrent, and differential photocurrent spectroscopy, are discussed. The results demonstrate considerable potential of DPVS for the nondestructive characterization of these structures at room temperature.

We have investigated an 850 nm GaAs/GaAlAs (001) vertical-cavity surface-emitting laser (VCSEL) structure using angle- and temperature-dependent surface photovoltage spectroscopy (SPS). The SPS measurements were performed as functions of angle of incidence (0° ≤ θ ≤ 60°) and temperature (25° C ≤ T ≤ 215° C) for both the metal–insulator–semiconductor (MIS) and wavelength-modulated MIS configurations. Angle-dependent reflectance (R) measurements have also been performed to illustrate the superior features of the SPS technique. The SPS spectra exhibit both the fundamental conduction to heavy-hole excitonic transition of quantum well and cavity mode (CM) plus a rich interference pattern related to the mirror stacks, whereas in the R spectra only the CM and interference features are clearly visible. The variations of SPS spectra as functions of incident angle and temperature enable exploration of light emission from the quantum well confined in a microcavity with relation to the Fabry–Pérot cavity mode. The results demonstrate considerable potential of SPS for the contactless and nondestructive characterization of VCSEL structures.

Articles you may be interested inRoom temperature circularly polarized lasing in an optically spin injected vertical-cavity surface-emitting laser with (110) GaAs quantum wells Appl. Phys. Lett. 98, 081113 (2011); 10.1063/1.3554760 Differential surface photovoltage spectroscopy characterization of a 1.3 μm InGaAlAs/InP vertical-cavity surfaceemitting laser structureResonances between the cavity mode and five excitonic transitions in an In x Ga 1−x As/GaAs/AlAs/AlGaAs vertical-cavity surface-emitting laser structure using photomodulated reflectance