Quality improvement of the dual-wavelength signals in DLOB via power equalization

Abstract

The data packet buffering can be implemented in dual loop optical buffer (DLOB) through cross-phase modulation (XPM) between the control signal and the data packets. However, the output equality of dual wavelength signals will degrade due to the unbalanced gain and phase shift. This problem can be resolved by power equalization using the saturation characteristics of SOA. The data packets with 2.5 Gb/s can be buffered in DLOB for 16 cycles corresponding to 16.5 s.The extinction ratio of the output packet is 8 dB while the S/N is 8.1 dB.As the traffic of information and multi-services increases, broadband and high capacity transmission networks have attracted extensive research interests. As a result, dense wavelength division multiplexing (DWDM) systems and optical packet switching (OPS) systems that provide high capacity and flexibility over the entire network have become a key option in the next generation networks. Optical buffer [1][2][3][4][5][6] is one of the most important components in OPS networks as it can solve the contention of the data packets in the optical domain without O/E/O conversion. Practical buffers are implemented based on slow-light effect [4,5] , fiber delay lines (FDL) [6] , or fiber loop [7][8][9][10][11][12][13][14] . To the best of our knowledge, all of the above configurations are only suitable for single wavelength signal buffering. With the development of the wavelength division multiplexing (WDM) technology, multi-wavelength buffers are imminently needed. In this paper, dualwavelength signal buffering in DLOB based on a collinear 3 3 fiber coupler is presented and experimentally demonstrated [9][10][11] . By introducing an SOA after the DWDM and utilizing the gain saturation characteristics of SOA, the uniform output bits power could be obtained, and the distortions of output pulses can be successfully mitigated and the buffer performance is greatly improved.The experimental setup for dual-wavelength signal buffering is shown in Fig.

Analysis of fibre-loop optical buffers with a void-avoiding schedule

“…Many researchers (listed in [4]) have worked on implementations similar to the one proposed in [11]; recently, also a second type of implementation with dual-loop optical buffers (DLOB) gained attention [13,6,22,24]. Both types can accommodate for a single packet and are arranged in parallel in the design of loop optical buffers.…”