320 Gb/s Phase-Transparent Wavelength Conversion in a Silicon Nanowire H. Hu, H. Ji, M. Galili, M. Pu, H.C.H. Mulvad, L. K. Oxenløwe, K. Yvind, J. M. Hvam and P. Jeppesen DTU Fotonik, Technical University of Denmark, Building 343, DK-2800 Lyngby, Denmark huhao@fotonik.dtu.dk Abstract: All-optical wavelength conversion for a 320 Gb/s RZ-DPSK signal is demonstrated based on four wave mixing in a silicon nanowire. BER better than 10 -9 is achieved for the wavelength converted RZ-DPSK signal. OCIS codes: (060.2330) Fiber optics communications; (230.7405) Wavelength conversion devices 1. Introduction Wavelength conversion is a key network functionality in future dynamic wavelength division multiplexing (WDM) networks. On the other hand, advanced modulation formats such as differential-phase-shift-keying (DPSK) and differential-quaternary-phase-shift-keying (DQPSK) have become promising candidates for future high-speed communication systems. As a result, phase-transparent wavelength conversion will be highly desirable. High speed phase-transparent wavelength conversion has been demonstrated in several schemes including four wave mixing (FWM) or cascaded χ (2) processes. Four wave mixing for phase preserving high speed wavelength conversion has been demonstrated in highly non-linear fiber (HNLF) for conversion of a 640 Gb/s DPSK data [1]. Cascaded χ (2) effects in a periodically poled Lithium Niobate (PPLN) waveguide has been demonstrated for phase preserving conversion up to 320 Gb/s DQPSK [2-3]. Wavelength conversion in silicon waveguides has attracted considerable research interests due to the very large operating bandwidth which can be achieved, ultra-high-speed operation, complementary metal-oxide-semiconductor (CMOS) compatibility, compactness and integration potential [4-8]. Wavelength conversion of intensity modulated signals based on silicon waveguides has been demonstrated with bit error rate (BER) results at 80 Gb/s in [7] and the potential for scaling this to 160 Gb/s and 320 Gb/s is indicated in [7-8]. Wavelength conversion of phase modulated data signals in silicon has so far not been demonstrated. Furthermore wavelength conversion in silicon capable of preserving high bit integrity (BER<10 -9 ) has only been demonstrated at 80 Gb/s with a penalty in received power of 11.1 dB at BER=10 -9 . In this paper, we experimentally demonstrate wavelength conversion of 160 Gb/s and 320 Gb/s DPSK data based on FWM in a silicon nanowire. For 160 Gb/s conversion a BER of 10 -9 is achieved with only 2.5 dB penalty in required receiver power compared to the original signal. For 320 Gb/s conversion BER of 10 -9 is achieved for 16 of the 32 OTDM channels and all channels achieved a BER better than 10 -8 . 2. Experimental setup 1557 nm ERGO PGL 5 nm 1542 nm 10 GHz DF-HNLF All-optical Wavelength Converter 5 nm OBF 3dB OC Notch filter 1550 nm 1543 nm 20 nm CW 1.3 nm 1550 nm OBF 1557 nm 10 Gb/s, PRBS 2 31 -1 OBF 10 Gb/s 320 Gb/s MUX ×32 PC PC MZM HNLF NOLM 1.3 nm 320 Gb/s RZ-DPSK transmitter 320 Gb/s DPSK receiver BPD Error Analyzer 1543 nm 5 nm Silicon Nanowire Control pulse 10 GHz, 1560 nm 10 GHz Control 1.3 ps, 1560 nm DLI 1557 nm ERGO PGL 5 nm 1542 nm 10 GHz DF-HNLF All-optical Wavelength Converter 5 nm OBF 3dB OC Notch filter 1550 nm 1543 nm 20 nm CW 1.3 nm 1550 nm OBF 1557 nm 10 Gb/s, PRBS 2 31 -1 OBF 10 Gb/s 320 Gb/s MUX ×32 PC PC MZM HNLF NOLM 1.3 nm 1.3 nm 320 Gb/s RZ-DPSK transmitter 320 Gb/s DPSK receiver BPD Error Analyzer 1543 nm 5 nm Silicon Nanowire Control pulse 10 GHz, 1560 nm 10 GHz Control 1.3 ps, 1560 nm DLI Fig. 1. Experimental setup for wavelength conversion of a 320 Gb/s RZ-DPSK signal. The key device in the wavelength converter is a nano-engineered silicon nanowire, which is 3.6 mm long and has a cross-sectional dimension of 250 nm × 450 nm. The device has a silicon-on-insulator (SOI) structure, with the silicon nanowire placed on a SiO 2 /Si substrate. The width at the end of the silicon nanowire is tapered from 450 nm to a tiny tip end of 40 nm so that the guided mode will expand into a polymer waveguide, surrounding the SOI waveguide and the taper. The 3.6-mm length of the nanowire includes the tapering sections, which are about 0.3 mm OWG6.pdf OSA/OFC/NFOEC 2011 OWG6.pdf