A Hybrid Integrated Short-External-Cavity Chaotic Semiconductor Laser

A simple design of a hybrid integrated short-external-cavity chaotic semiconductor laser module is presented and fabricated. A distributed feedback laser chip is directed to the transflective mirror through a collimating micro-lens, and a part of the light is reflected by the mirror into the laser chip to induce chaos. Transmitted through the mirror, the generated chaotic light is coupled into a pigtail fiber as output by a focusing micro-lens. It should be pointed out that the part between the transflective mirror and the emitting surface of the chip works as a short external straight feedback cavity. All the components above together with chip submount, heat sink, and thermoelectric cooler are encapsulated by a commercial 14-pin butterfly package. In our experimental fabrication, the intensity reflectivity of the transflective mirror is optimized as 5% and the external-cavity length is 2 mm. Experimental tests show that chaotic light with a bandwidth larger than 4.5 GHz is readily obtained from the chaotic laser module by adjusting laser bias current.