Self-oscillating optical mixer receiver

It has been predicted that a semiconductor laser can be operated simultaneously as both a local oscillator (LO) and an optical mixer by extracting a microwave heterodyne signal from the bias current. Injection-current modulation has recently been demonstrated in a diode laser in response to an optical probe. The authors report the first use of this effect to detect a modulated optical signal. They present measurements of the sensitivity of a self-oscillating mixer receiver for amplitude-shift-keyed-modulated signals at 400 Mb/s. This technique offers many of the advantages of conventional heterodyne detection without the need for an optical coupler or photodiode.