Opt Quant Electron (2011) 42:297–311 DOI 10.1007/s11082-011-9459-6 Fiber optic loop buffer switch incorporating 3R regeneration Rajiv Srivastava · Yatindra Nath Singh Received: 22 January 2010 / Accepted: 17 March 2011 / Published online: 31 March 2011 © Springer Science+Business Media, LLC. 2011 Abstract In this paper, an all-optical regenerator based, photonic packet switch architec- ture, which consists of fiber loop for the storage of the contending packets, is proposed. In the loop buffer, the available buffer space may not be fully utilized due to the re-circulation limit (maximum number of re-circulations that data can take before it can be correctly received at the output). The re-circulation limit arises due to the accumulated ASE (amplified spontane- ous emission) noise of the optical amplifier and crosstalk of the optical components. This limit can be counteract by placing a pool of regenerators inside the buffer, which regenerates the signal after some fixed number of re-circulations. As optical regenerators are costly devices, hence they should be placed optimally in the buffer. To do so, in this paper an expression is presented to evaluate the minimum number of required regenerators, to be placed optimally in the buffer for different buffer configurations (B) and re-circulation limits (K), such that full buffer capacity can be utilized without any re-circulation constraints. The simulation results in terms of packet loss probability are presented by considering the detrimental effect of re-circulation limits. Finally, advantages gain due to the regenerator placement inside the buffer are shown. Keywords Tunable wavelength converters · Optical packet switch · Multi-wavelength buffer · Optical regenerator · Loop buffer 1 Introduction Optical packet switching (OPS) is a connectionless networking solution that provides very fine granularity and optimum bandwidth utilization, which in a core network can provide very high throughput, data rate transparency and low latency, etc. Still, all-optical switches are R. Srivastava Indian Institute of Technology, Rajasthan, Jodhpur, Rajasthan, India R. Srivastava (B ) · Y. N. Singh Indian Institute of Technology, Kanpur, Kanpur, U.P., India e-mail: rajivs@iitk.ac.in 123