CAVITY LENGTH DEPENDENCE OF HIGH-SPEED 1.55-MU-M MULTIPLE-QUANTUM-WELL LASER-DIODE CHARACTERISTICS

Spontaneous emission spectra below threshold were measured from the si de wall of laser diodes to extract laser design parameters such as cav ity length dependence of gain, linewidth enhancement factor, and seria l resistance, The threshold current varies according to the change of cavity length, and thus, the lasing peak shifts and the serial resista nce changes, It is interesting that the linewidth enhancement factor, however, is not deteriorated by shortening cavity length, The short ca vity length would rather improve the linewidth enhancement factor main ly by shifting the lasing peak to smaller wavelength side, where the l inewidth enhancement factor is inherently low.