Demonstration of a low-cost cascade tunable semiconductor DFB laser

A low-cost cascade tunable semiconductor distributed feedback (DFB) laser is proposed based on the reconstruction equivalent chirp (REC) technique and experimentally demonstrated for the first time. It covers 9nm continuous tuning range by changing the temperature. The side mode suppression ratios are above 42dB over the tuning range. The current and temperature coefficients of wavelength tuning are 0.0124nm/mA and 0.0875nm/°C, respectively. The grating is fabricated by holographic exposure and conventional lithography, so the cost is very low. The results indicate that REC technique is promising to fabricate tunable DFB lasers which can meet the requirement of access networks. The tuning range can also be extended by using more sections.