Injection locking-based pump recovery for phase-sensitive amplified links

Abstract

Abstract:An injection locking-based pump recovery system for phase-sensitive amplified links, capable of handling 40 dB effective span loss, is demonstrated. Measurements with 10 GBd DQPSK signals show penalty-free recovery of a pump wave, phase modulated with two sinusoidal RF-tones at 0.1 GHz and 0.3 GHz, with 64 dB amplification. The operating power limit for the pump recovery system is experimentally investigated and is governed by the noise transfer and phase modulation transfer characteristics of the injection-locked laser. The corresponding link penalties are explained and quantified. This system enables, for the first time, WDM compatible phase-sensitive amplified links over significant lengths. References and links 1. C. M. Caves, "Quantum limits on noise in linear amplifiers," Phys. Rev. D 26, 1817Rev. D 26, -1839Rev. D 26, (1982. 2. E. Desurvire, Erbium-doped Fiber Amplifiers, (John Wiley & Sons, 1994). 3. W. Imajuku, A. Takada, and Y. Yamabayashi, "Low-noise amplification under the 3dB noise figure in high-gain phase-sensitive fibre amplifier," Electron. Lett 35, 1954Lett 35, -1955Lett 35, (1999 J. Richardson, "Detailed characterization of a fiber-optic parametric amplifier in phase-sensitive and phaseinsensitive operation," Opt. Express 18, 4130-4137 (2010). 8. M. Vasilyev, "Distributed phase-sensitive amplification," Opt. Express 13, 7563-7571 (2005). 9. R. Tang, P. Devgan, V. S. Grigoryan, and P. Kumar, "Inline frequency-non-degenerate phase-sensitive fibre parametric amplifier for fibre-optic communication," Electron.

Phase-sensitive amplifier link with distributed Raman amplification

“…The pump recovery stage was based on an injection locked laser followed by a high-power EDFA and a phase-locked loop (PLL). The PLL operated by applying a 40 kHz phase dithering tone on the pump using a piezoelectric fiber stretcher and maximizing the PSA gain by keeping the relative phase between signal, idler and pump constant, more details on the PLL implementation can be found in [22]. Thus, the FOPA acted as a PSA on the second and all subsequent round trips in the loop.…”

Long-haul (3465 km) transmission of a 10 GBd QPSK signal with low noise phase-sensitive in-line amplification

“…The signal and pump launched into the loop were attenuated using variable optical attenuators (VOAs) to match the power level after following circulations. Before the in-line amplifier the pump was separated from the signal (and idler) and passed into a pump recovery system for amplification and regeneration 8 . The signal (and idler) was passed through another arm and then combined with the high-power pump before being launched into fiber optical parametric amplifier (FOPA) which was implemented with strained highly nonlinear fiber (HNLF) with in-line isolators 9 .…”

Impact of Optical Phase Conjugation on the Nonlinear Shannon Limit

“…At the receiver, a phase sensitive amplifier, which essentially interferometrically combines an input signal and idler (the signals conjugate copy), may be used to perform the required coherent addition [28,29], although pump phase locking is required [30]. By combining all optical conjugate copy generation and receiver processing, the combined benefits of nonlinearity mitigation and reduced noise figure are simultaneously achieved [31], such that the signal to noise ratio gain over a conventional single channel system using phase insensitive amplifiers would approach 4(3/2 snr0) 3/2 .…”