| Over the last ten years, transmitting multiple wavelength channels down an optical fiber in a wavelength-division-multiplexed (WDM) system has emerged as a powerful technique to increase the information capacity of optical networks. As WDM systems are scaled, creating large networks with dynamic traffic patterns, these systems encounter wavelength contention, resulting in blocking of one or more channels. The ability to dynamically change the wavelength of an optical channel alleviates wavelength contention and significantly improves network performance. This talk explores two generations of optically-controlled electroabsorption modulators that can be used for wavelength conversion applications and offer significant advantages over other wavelength conversion techniques. These devices consume low electrical and optical powers and require simple electrical packaging. Furthermore, they possess electrical reconfigurability, two-dimensional scalability, polarization-independent operation, and the ability to monitor network performance.; The first generation device was a GaAs-based, single diode, surface-normal optically-controlled electroabsorption modulator. The optical switching relies on electric field screening of multiple quantum wells and diffusive electrical conduction. We present a theoretical investigation of this device, illustrating the possibility of performing wavelength conversion at switching frequencies exceeding 50 GHz. As a proof-of-concept demonstration, we present experimental results of wavelength-converting optical switching at frequencies up to 2.5 GHz using only 2.4 mW of optical power.; The second generation device was an InP-based, multicomponent optoelectronic integrated circuit that eliminates the design tradeoffs present in the first generation device. We developed a fabrication process, incorporating a selective area regrowth technique, that monolithically integrates a waveguide electroabsorption modulator and a surface-illuminated photodetector into a compact circuit for performing optical switching and wavelength conversion. Using mW-level optical powers, we demonstrated optically-controlled switching up to 2.5 Gb/s with >10 dB extinction ratio. Wavelength conversion over the entire center telecommunication band (1530–1565 nm) was demonstrated at 1.25 Gb/s with >10 dB extinction ratio using a fixed input optical power of 5.6 mW. We theoretically investigated high-speed operation at 10–40 Gb/s and present the device requirements and optimization criteria for achieving these speeds. This work is the first step towards creating a chip-scale multichannel, wavelength-converting, optical crossbar switch. |
