Ultracompact all-optical XOR logic gate in a slow-light silicon photonic crystal waveguide

C Husko,J Li,T F Krauss,B J Eggleton,T D Vo,B Corcoran

doi:10.1364/oe.19.020681

Abstract

We demonstrate an ultracompact, chip-based, all-optical exclusive-OR (XOR) logic gate via slow-light enhanced four-wave mixing (FWM) in a silicon photonic crystal waveguide (PhCWG). We achieve error-free operation (<10⁻⁹) for 40 Gbit/s differential phase-shift keying (DPSK) signals with a 2.8 dB power penalty. Slowing the light to vg = c/32 enables a FWM conversion efficiency, η, of -30 dB for a 396 μm device. The nonlinear FWM process is enhanced by 20 dB compared to a relatively fast mode of vg = c/5. The XOR operation requires ≈ 41 mW, corresponding to a switching energy of 1 pJ/bit. We compare the slow-light PhCWG device performance with experimentally demonstrated XOR DPSK logic gates in other platforms and discuss scaling the device operation to higher bit-rates. The ultracompact structure suggests the potential for device integration.

Highlights

All-optical nonlinear signal processing is advancing rapidly, with recent demonstrations of functionalities such as all-optical signal regeneration [1], THz bandwidth multi-impairment monitoring [2], and 1.28 Terabit/s demultiplexing [3]
We demonstrate an ultracompact, chip-based, all-optical exclusive-OR (XOR) logic gate via slow-light enhanced four-wave mixing (FWM) in a silicon photonic crystal waveguide (PhCWG)
All-optical logic functions employing differential phase-shift keying (DPSK) have been demonstrated in a variety of platforms: highly nonlinear silica fiber (HNLF) [7], semiconductor optical amplifiers (SOAs) [8, 9], and periodically poled lithium niobate (PPLN) [10]

Summary

Introduction

All-optical nonlinear signal processing is advancing rapidly, with recent demonstrations of functionalities such as all-optical signal regeneration [1], THz bandwidth multi-impairment monitoring [2], and 1.28 Terabit/s demultiplexing [3]. All-optical logic functions employing DPSK have been demonstrated in a variety of platforms: highly nonlinear silica fiber (HNLF) [7], semiconductor optical amplifiers (SOAs) [8, 9], and periodically poled lithium niobate (PPLN) [10]. These platforms, experience different limitations, including stimulated Brillouin scattering in HNLF, free-carrier patterning effects and a bias current that adds to the energy requirements of SOA, and, in the case of PPLN, temperature control, though a route forward has been suggested [11]

Results

Discussion

Conclusion