Short-pulse generation with broad-band tunability from semiconductor lasers in an external ring cavity

Short optical pulses are generated by actively mode locking semiconductor l asers in an external ring cavity with a very broad tuning range from 795 to 857 nm. The wide tunability is possible because the gain bandwidth is broa dened by the use of asymmetric dual quantum wells for the semiconductor las er material. Assuming a Gaussian shape, the generated pulses have pulsewidt hs of 13-21 ps and spectral widths of 2-4.5 Angstrom for the tuning range. The mode-locked spectrum contains almost no amplified spontaneous emission noise.