Optical Properties of DBR-Lasers

We have fabricated the InGaAsP/InP DBR-lasers with the wavelength range of 1.5μm, and investigated their optoelectronic properties. High sub-mode suppression ratios of exceeding 35 dB, and very narrow spectral linewidths less than 10 MHz were obtained. Wavelengthtuning was performed by an injection of tuning current in Bragg reflector region. The maximum continuous tuning range was 1.9 nm. In addition, the effects of anti-reflection (AR) coating on the lasing characteristics were investigated. The experimental results show that the AR-coating can improve the sub-mode suppression ratio by about 5 dB. The output power of the lasers with AR-coating are about 1.5 times larger than that of the lasers without AR-coating. These results agree well with theoretical calculations.