Abstract

Short, high peak power optical pulses in the wavelength region λ=1.3-1.6μm are potentially attractive for very-high bit-rate lightwave systems and signal processing. InGaAsP/InP lasers, the most widely used semiconductor lasers for this wavelength range, have previously been actively modelocked by current modulating the diode in a passive, extended cavity.³ The achievement of low loss², high speed titanium-diffused lithium niobate waveguide optical switches has made possible a new approach to active modelocking of semiconductor lasers³. We have fabricated a low-loss, broadband Ti:LiNbO₃ waveguide directional coupler switch that is coupled to the AR coated facet of a DC biased InGaAsP/InP diode. By driving the switch with a sinusoidol signal, we have modelocked the composite cavity to produce a train of 22 psec wide (FWHM) pulses at repetition rates as high as 7.2 GHz. This new method of modelocking semiconductors lasers offers important advantages including the potential for combined modelocking/cavity dumping, ring laser geometry and electrically tunable modelocked pulses. In addition, the generated pulses could be multiplexed or encoded with another Ti:LiNbO₃ switch/modulator integrated on the same chip.

© 1984 Optical Society of America