THz-bandwidth tunable slow light in semiconductor optical amplifiers.

We report tunable fractional delays of 250% for 700 fs pulses propagating in a 1.55 mum semiconductor optical amplifier at room temperature. This large fractional delay is attributed to a spectral hole created by the propagating pulses for pulses with duration shorter than the carrier heating relaxation time. Delay can be tuned electrically by adjusting the current with low amplitude variation across the tuning range.