Low-chirp and high-power 1.55-μm strained-quantum-well complex-coupled DFB laser

High-power, low-chirp, and low-threshold current characteristics of 1.55 μm complex-coupled compressively strained InGaAsP quantum-well DFB laser with a loss grating are presented. Kink-free light-current characteristics with single-mode power over 40 mW are demonstrated for uncoated devices. A relatively low threshold current of 10 mA and a high slope efficiency of 0.23 W/A have been obtained even with the loss grating employed. Stable single-mode emission was demonstrated with a side mode suppression ratio up to 54 dB, a low chirp of less than 0.3 nm under 1 Gb/s pseudorandom digital modulation and a spectral linewidth of 8 MHz.