Stable Longitudinal Mode Research Articles

Longitudinal mode stability difference in Se- and Si-doped AlGaAs lasers

The longitudinal mode behavior of AlGaAs lasers with n-type cladding layers doped with Se and Si is reported. The longitudinal mode of the lasers with highly Se-doped cladding layer is stabilized, and large hysteresis of mode jump is observed as temperature changes. In the case of highly Si-doped cladding layers, however, the mode hops to the adjacent one and no hysteresis is observed. These phenomena are explained by the difference in thermal activation energy between Se- and Si-related DX centers.

Stable cw operation at room temperature of a 1.5-μm wavelength multiple quantum well laser on a Si substrate

Room-temperature cw operation of an InGaAs/InGaAsP multiple quantum well (MQW) laser diode on a Si substrate is reported. The MQW laser emits at a 1.54 μm wavelength and exhibits no degradation after over 2000 h of operation. Employing a hybrid organometallic vapor phase epitaxy/vapor mixing epitaxy method and a layer structure for improving crystalline quality, high-quality MQW layers are obtained. A stable longitudinal mode spectrum demonstrates the effectiveness of the MQW active layer.

1.5 µm-Long-Wavelength Multiple Quantum Well Laser on a Si Substrate

Room-temperature cw operation of an InGaAs/InGaAsP multiple quantum well (MQW) laser diode on a Si substrate is reported. The MQW laser emits at 1.54-µm wavelength and exhibits no degradation after over 1,000 hours of operation. Employing a hybrid organometallic vapor-phase epitaxy/vapor mixing epitaxy method and a layer structure for improving crystalline quality, high-quality MQW were obtained. The stable longitudinal mode spectrum demonstrates the effectiveness of the MQW active layer and results in low-intensity noise. Annealing phenomena under cw operation are also discussed.

A GaInAsP/InP tapered-waveguide semiconductor laser amplifier integrated with a 1.5 mu m distributed feedback laser

A GaInAsP/InP index-guided type tapered-waveguide traveling-wave semiconductor laser amplifier (TTW-SLA) with exponential taper structure was realized for the first time and its integration with a 1.5 mu m wavelength phase adjusted DFB laser was demonstrated. A reasonable amount of the single-pass gain, which was limited by the residual reflectivity at the output end of the amplifier region, was obtained with no serious problem with the lasing spectrum. A narrow beam divergence of FWHM=5.5 degrees and stable longitudinal mode operation were obtained with the output waveguide width of 20 mu m by adopting both a window structure and 7 degrees angled facets. This value agrees well with the theoretically calculated one and proves that single transverse-mode propagation can be attained by an exponentially tapered TTW-SLA with a very wide output end. >

A new composite-cavity laser with two different waveguide cores for stable longitudinal mode operation

We have developed a new composite-cavity laser with two different waveguide cores connected near the front mirror in the same cladding. This composite cavity has a built-in structure that is capable of giving high mode selectivity because of strongly modulated reflectivity of the front mirror. The laser shows very stable single longitudinal mode operation in a temperature range as wide as about 50 °C for output powers from 3 to 100 mW without mode hopping.

Optical properties of superlattice and MQW laser diode

MBE grown GaAs–AlxGa1−xAs superlattice structure was investigated in terms of crystallography (x‐ray diffraction and direct lattice‐image observation by TEM) and optical properties (controllability of Eg, oppoiste Burstein shift, structure dependent refractive index and room‐temperature exciton). New device properties are described for an MQW laser diode/waveguide. These include anisotropic gain, low absorption loss, and stable longitudinal mode oscillation under high‐speed modulation. An MQW laser diode in the long wavelength region is presented, which is made using the GaSb–AlxGa1−xSb material system. Future prospects are also described.

Optical properties of superlattice and MQW laser diode

Abstract MBE grown GaAs-AlχGa1-χAs superlattice structure is investigated from the view points of crystallography (X-ray diffraction and direct lattice-image observation by TEM), and optical properties (controllability of E , opposite Burstein shift, structure dependent refractive index and room-temperature exciton). New device properties of an MQW laser diode/waveguide are described, which are an anisotropic gain, low absorption loss and stable longitudinal mode oscillation under high-speed modulation. Long wavelength region MQW laser diode is presented which is made from GaSb-AlχGa1-χSb material system. Some future prospects are given.