Kiyoshi Fujihara

Enhanced relaxation oscillation frequency of 1.3 /spl mu/m strained-layer multiquantum well lasers

Dependence of relaxation oscillation frequency (f/sub r/) on the bandgap wavelength of InGaAsP barrier layers (/spl lambda//sub g//sup b/) and number of quantum wells (N/sub w/) were investigated for the first time, for 1.3 /spl mu/m InGaAsP/InGaAsP compressively strained multiquantum well (MQW) lasers. 1.3 times higher f/sub r/ was confirmed for strained-layer MQW lasers with large N/sub w/ (N/sub w//spl ges/7) and wide bandgap barrier layers (/spl lambda//sub g//sup b/=1.05 /spl mu/m) at the same injection level, compared with unstrained MQW lasers having the same well thicknesses and the same emitting wavelength. This enhancement mainly results from increased differential gain due to strain effects separated from the quantum-size effect.<<ETX>>

Low distortion 1.3 /spl mu/m strained-layer MQW-DFB laser for AM-SCM transmission systems with large channel capacity

1.3-/spl mu/m strained-layer multiquantum-well distributed-feedback (SL-MQW-DFB) lasers with extremely low distortion and low noise characteristics up to high output-power as well as over wide frequency range were successfully fabricated. This was achieved by both the high relaxation oscillation frequency (f/sub r/) characteristics of the laser with the optimized SL-MQW active structure and the suppression of nonradiative current with relatively long laser cavity length. By using the SL-MQW laser with a 400-/spl mu/m long cavity as a light source for CATV transmission system, high quality AM-SCM transmissions with the largest channel capacity (151 channel) was demonstrated due to low distortion characteristics at high output power. Also, for the laser with 300 /spl mu/m long cavity, extremely low bias-current operation (17 mA above threshold) is realized in high quality 100 channel AMSCM transmissions, due to high f/sub r/ at low bias-current.

Rapid degradation of InGaAsP/InP laser diodes due to copper contamination

The influence of copper contamination upon rapid degradation of InGaAsP/InP buried-heterostructure laser diodes under accelerated high stress aging test is investigated, for the first time. Strong correlation between the quantity of contaminated copper in the laser diodes and the degradation of lasing characteristics is confirmed.

151-channel AM-FDM transmission using 1.3 /spl mu/m strained-layer MQW-DFB laser with high optical output power operation

1.3 /spl mu/m strained-layer multi-quantum well distributed-feedback (SL-MQW-DFB) lasers with low distortion characteristics over wide frequency range even at high optical output power operation have been successfully fabricated. This is achieved by both the high relaxation oscillation frequency characteristics of the SL-MQW active structure and the suppression of non-radiative current in the relatively long laser cavity. By using the laser as a light source for CATV transmission system, high quality AM-FDM transmissions with the largest channel capacity (151ch) have been demonstrated.<<ETX>>

High characteristic temperature 1.48 /spl mu/m strained-layer MQW laser diode with wide bandgap barrier layers

In order to realize high temperature operation of a 1.48 /spl mu/m high power multi-quantum well laser diode, the carrier overflow from the well layers at high temperature should be reduced. This paper shows that utilization of wide bandgap barrier layers in the multi-quantum well structure is effective for this purpose. A highest characteristic temperature of 75 K is achieved.<<ETX>>

1.3 /spl mu/m strained-layer MQW-DFB laser with low noise and low distortion characteristics for 100-channel CATV transmission

1.3 /spl mu/m strained-layer MQW-DFB lasers with large differential gain have been successfully fabricated. The lasers exhibit low distortion and low noise characteristics over wide frequency range even under low bias-current level. These characteristics result from largely improved dependence of relaxation oscillation frequency (f/sub r/) on injection current, due to strain effects. By using the laser as a signal source in CATV systems, high quality AM-FDM transmissions with largest recorded channel capacity (100 ch) have been demonstrated under an extremely low bias-current of 17 mA above threshold current.<<ETX>>