Bistable semiconductor lasers have potential applications in future optical communication, optical switching, optical computing, and so on [I] Although gain saturation alone could account for the bistability, the inclusion of absorption saturation could make the bistability easier to occur [2]. As a result, multi-elecbode semiconductor lasers are usually used for optical bistability. In this work, we report that bistability exists in the semiconductor lasers without multiple sections. Using multiple quantum wells of different widths, both gain quenching and saturable absorption could occur in the same region for bistability The semiconductor lasers that exhibit optical bistability have four quantum wells with their widths 20& 33.4, 56& and l 2 5 G respectively, separated by 150 A Ab,%&barrier. An external-cavity configuration with broadband tunability was used for the bistability experiment. Different behaviors of bistability had heen discovered for different wavelengths. Fig 1 shows an L-I curve with obvious bistability. The details of experiments will be discussed in the presentation. 7 0 816nm 6 Fig 1 An L-I curve at lasing wavelength of 816 nm that exhibits hysteresis. Currenl(m.4) References: [I] Hitoshi Kawaguchi, IEEE J. Select. Topics Quantum [2] Ching-Ameaiq phone: (3742) 556383, Fax: (3742) 151087The resonant =tun of the excitation of surface ele3"apdic waves (SEWs), i.e. the r e s " dependence of the reflectivity on the incident radiation wavevedor component parallel to the interface (swhe), k, leads to the nonlinear phenomena arising and particularly optical biand multi-stability ~ppearance at relatively small nonlinearities. At such nonlinvinties the fieldinduced variation of SEW wavevectoi, K, becomes comparable with the width, lm(K), of the mentioned geometrical (angular) r e m " .In this paper the thwry of optical bi-and multistability at the excitation of TM-polarized SEWs via Kre~~chmann attenuated total reflection (Am) nchemc (glass prism-metal film-dielechic) in which the dielectric exhibits a relatively small one. or huo-photon resonant nonlinearity is presented. The system of equations describing the excitation of nonlinear SEWs is presented in eneral fom for arbitrq type of nonline& by means of SEW wavevector nonlinear term, 9, It is the Same form which in e m of cubic nonlinearity has ban presented in [I]. The value of K #' is determined via [2] :
K" -K O I [~" ( i ) + i K , K , ' P~( 1 ) I . X P ( -K , z )~,where x is the SEW propagation direetion, z is the direction of perpendicular to metaldielectric intecfce, p"'. is the amplitude of medium nonlinear QolariZatiOn, K, is the linear term of SEW wmwector,L, = (K: -( m / c ) '~, ] ' ' . zd is the dielectric pemimvity ofnonlinear medium. In the case of one-photon resonance on the dependence of reflectivity on incident radiation intensity the hysteresis loop of aptkal bistability arises when the concenhalion of resonant putides exceeds the corresponding threshold. That threshold is the function of frequency and wwevectm mismatches ( o -m 2 ,...
