Monolithically Integrated Nonlinear Sagnac Interferometer and its Application as a 20 Gbit/s All-Optical Demultiplexer

Abstract

All-optical switching devices are expected to play an important role in future optical time-division multiplexing (OTDM) networks. Interferometer arrangements consisting of one or two semiconductor laser amplifiers (SLA) are very attractive for this purpose. Here, the cross-phase modulation due to the gain-saturation nonlinearity of SLAs provides the differential phase shift required for interferometric switching. The first of such devices was configured as a Sagnac interferometer by using an SLA in a fiber loop mirror (SLALOM) [1], Subsequently, SLALOM devices were used as demulitiplexers in high bit rate OTDM experiments [2-5], So far, these devices have been assembled using discrete SLA components. Other interferometer arrangements like Mach-Zehnder interferometer (MZI) or Michelson interferometer with SLAs provide additional flexibility but require their realization as integrated devices for stable operation. Recently, we developed an integrated MZI device and demonstrated its use in 40 Gbit/s to 5 Gbit/s demultiplexing and add/drop multiplexing experiments [6-7], In this paper, we report the first monolithically integrated nonlinear Sagnac interferometer (NSI) and its application as a 20 Gbit/s all-optical demultiplexer. Such a demultiplexer requires only half the number of SLAs and 3-dB couplers as compared to the MZI devices.