Optical bistability in distributed feedback semiconductor laser amplifiers

New theoretical and experimental results are presented for optical bistability in distributed feedback amplifiers at 1.5 ¿¿m. The onset of bistability occurs at input powers as low as 1 ¿¿W, a factor of about 1000 times less than the input predicted for passive DFB structures. The transient response exhibits a large spike as the amplifier goes through a resonance, in good agreement with the theoretical prediction.