Abstract: The output polarization of a twin guide semiconductor laser is switched either by controlling the operating current of both guides or by injecting an optical signal. Twin-stripe and twin-ridge lasers of InGaAsP are described. True polarization bistability is reported for a range of devices: the effect is temperature insensitive.

Abstract: An opto-electronic switch which shows a good signal rejection ratio between modes is also of particularly small dimensions. The switch comprises a semiconductor laser 1 having four contacts 12, 12', 13, 13' which provide gain guiding under two stripe windows 18, 19. By varying the bias currents supplied to the individual contacts 12, 12', 13, 13', or inputting optical control signals to the waveguiding channels under the stripe windows 18, 19, different configurations of optical output from the laser 1 can be achieved. The two contacts, 12, 12' and 13, 13', associated with each stripe window 18, 19 are effectively a signal stripe contact with a discontinuity. It is thought that diffractive transverse coupling at the discontinuity allows the use of a shorter device than in known directional switches. With feedback, the switch operates as a memory device. The switch finds particular application in optical communications, for instance in signal routing.