H. Kurakake

A 1.3 mm strained quantum well laser on a graded InGaAs buffer with a GaAs substrate

We grew a 1.3 μm strained-layer quantum well (SL-QW) laser with InGaP cladding layers on a lattice-relaxation buffer layer by metalorganic vapor phase epitaxy. For the lattice-relaxation buffer, we used a compositionally graded InGaAs/GaAs structure. The significantly reduced surface roughness of the InGaP cladding layers achieved by supplying a large amount of H2Se enables CW operation of our 1.3 μm SL-QW laser. We achieved a low threshold current of less than 10 mA and a high characteristic temperature of 100K around room temperature.

Effect of recombination in separate-confinement heterostructure (SCH) layers on temperature characteristics of semiconductor lasers

We investigated the effect of recombination in separate-confinement heterostructure (SCH) layers on the temperature characteristics of lasers. It was found that the large dependence of recombination on the threshold carrier density can be used to greatly reduce the characteristic temperature T/sub 0/. A reduction of recombination in the SCH layer is essential for a high-optical confinement factor in each well. To obtain a high-optical confinement factor in wells at a 1.3-/spl mu/m emission, we fabricated a laser having a wide bandgap cladding layer by introducing a hetero-epitaxial buffer layer. This laser exhibited a temperature characteristic between that of short and long-wavelength lasers, as was expected from the optical confinement factor per well.

Optimum asymmetric mirror facet structure for high-efficiency semiconductor lasers

A design theory for asymmetric mirror facet structure lasers that takes into account the spatial hole burning (SHB) effect along the cavity is presented. It is shown that the SHB effect reduces the external quantum efficiency in asymmetric mirror facet structure lasers, and the front facet reflectivity has an optimum value depending on the internal loss for high-efficiency operation. A slope efficiency of more than 50% has been obtained in lasers based on the new design theory. It is noted that nonuniform current injection is one of the most useful methods for increasing the external quantum efficiency, which is reduced by the SHB effect. >

1.3 /spl mu/m high T/sub 0/ strained MQW laser with AlGaInAs SCH layers on a hetero-epitaxial InGaAs buffer layer

The 1.3 /spl mu/m InGaP clad laser with AlGaInAs SCH layer was fabricated on a hetero-epitaxial InGaAs QW buffer layer. Due to high optical confinement, this laser showed a high characteristic temperature T/sub 0/ of 110 K.

CW operation of a 1.3-/spl mu/m strained quantum well laser on a graded InGaAs buffer with a GaAs substrate

We investigated MOVPE growth of 1.3 /spl mu/m lasing SL-QWs with InGaP cladding layers on the compositionally graded InGaAs buffer layers with GaAs substrate. We found that the surface roughness of the lower InGaP layer causes generation of many dislocations around the SL-QWs. This deteriorated the photoluminescence intensity of the active layer. The surface roughness of the InGaP layers was reduced by the highly H/sub 2/Se supply. The reduction of the surface roughness significantly suppresses the dislocations around the SL-QWs. This new technique realized the first CW-operation of the 1.3 /spl mu/m SL-QW laser with InGaP cladding layers. We achieved a low threshold current of 15 mA and more than 15 mW output power.

High T/sub 0/ 1.3 /spl mu/m InGaAs strained single quantum well laser with InGaP wide band-gap clad layers

1.3 /spl mu/m laser simulation taking hot carriers into account indicated the effectiveness of wide band-gap clad layers for improving laser performance. Lasers fabricated with InGaP cladding layers based on these calculations exhibited the high T/sub 0/ of 100 K.

The performances of (InAs)/sub 1//(GaAs)/sub 2/ short-period superlattice strained single-quantum-well laser on GaAs substrate

We fabricated an (InAs)/sub 1//(GaAs)/sub 2/ short-period superlattice (SPS) strained quantum-well laser at 1.07 /spl mu/m by MOVPE. The SPS active layer has 10 periods of (InAs)/sub 1//(/sub G/aAs)/sub 2/ and an average mismatch of over 2.2%. In highly strained conditions the device showed a lasing wavelength of 1.07 /spl mu/m, a threshold of 130 A/cm/sup 2/, and a characteristic temperature T/sub 0/ of 175 K. We measured the gain characteristic by the Hakki and Paoli method at LED conditions and obtained a high differential gain of 2.0/spl times/10/sup -15/ cm/sup 2/ at the threshold current. >

Semiconductor laser model based on moment method solutions of the Boltzmann transport equation

Semiconductor laser models based on density matrix theory have been frequently reported on and are useful in recognizing stimulation emission. However, most of these models use the two-discrete-level approximation, making it difficult to obtain a detailed description of the carrier distribution. The mechanism of the carrier distribution variations in semiconductor lasers will be discussed from the point of view of the Boltzmann transport equation with the relaxation time approximation, and its effect on laser performance will be demonstrated in this paper.

InGaAs/InGaAsP strained SQW LD grown on In/sub 0.05/Ga/sub 0.95/As ternary substrate

A uniform In/sub 0.05/Ga/sub 0.95/As ternary substrate was grown and InGaAs/InGaAsP SQW LDs were fabricated on the substrate for the first time. Low threshold current density of 222 A/cm/sup 2/ and an excellent characteristic temperature of 221 K were achieved.

1.07 /spl mu/m (InAs)/sub 1//(GaAs)/sub 2/short period superlattice strained quantum well ridge waveguide laser

High performance ridge waveguide lasers with (InAs)/sub 1//(GaAS)/sub 2/ short period superlattice (SPS) active layer have been fabricated. A characteristic temperature of 156K is obtained at 1.07 /spl mu/m wavelength.