An integrated holding-beam-at-transparency (hbat) configuration for semiconductor optical amplification or emission

An optical device for amplifying or emitting an optical beam of given wavelength comprises an optical source (20) in combination with a primary optical device (10) which is a semiconductor optical amplifier (SOA), a gain-clamped semiconductor optical amplifier (GCSOA), a sub-threshold gain-clamped semiconductor optical amplifier (SGCSOA), a laser diode (LD) or a superluminescent LED (SLED). The primary optical device (10) delivers an output signal of given wavelength called the signal beam and optionally receives an input beam at the same wavelength as the signal beam. Operation of the primary optical device (10) is assisted by a holding beam supplied by the optical source (20). The holding beam is of smaller wavelength than the signal beam, the holding beam wavelength being tuned close to the transparency wavelength of the primary optical device to provide a holding beam at transparency (HBAT) mode. The signal beam and the holding beam are collinear within the primary optical device (10) and within the optical source (20). The optical source and the SOA, GCSOA, SGCSOA or LD are integrated in a single semiconductor chip preferably in an in-line configuration. The optical source is transparent at the signal wavelength in the SOA, GCSOA, SGCSOA, LD or SLED. The inventive integrated HBAT configurations allow extremely fast, high-gain and low noise operation of the SOA's, GCSOA's or SGCSOA's. They are well-suited for high-power, low noise and high speed WDM applications. The inventive integrated HBAT scheme for LD's provides laser sources with damped relaxation oscillations. Such devices, under fast direct modulation, are suitable sources for the access and metro telecommunication network.