Optics Letters

Noise performance of a frequency nondegenerate phase-sensitive amplifier with unequalized inputs

Z. Tong, Carl Lundström, Magnus Karlsson, Michael Vasilyev, Peter A. Andrekson

Published Feb 24, 2011• 35 citations

Abstract

For the first time to our knowledge, the noise performance of a frequency nondegenerate phase-sensitive amplifier (PSA) with unequalized input powers has been experimentally characterized, based on a fiber-based parametric copier-PSA scheme. Two different noise-figure (NF) definitions-separate and combined NFs-are provided and compared. The results show that the separate NF of the weaker input wave is lower than that of the stronger wave due to the correlated-light nature. When considering the combined NF, the optimal noise performance (0 dB NF) is obtained only when the input powers are equal. Experiments agree well with the theoretical predictions.

DOI: 10.1364/ol.36.000722

Related papers

Ultralow Noise, Broadband Phase-Sensitive Optical Amplifiers, and Their Applications

Zhi Tong, Carl Lundström, Peter A. Andrekson +2 more

Frequency nondegenerate phase-sensitive amplifiers (PSAs) have the potential to realize broadband and noiseless amplification. However, the rigorous requirement of phase- and wavelength-locking of the input waves has significantly hampered their progress. In this paper, we review recent research on this type of optical amplifier. This work is based on a copier-PSA scheme, which consists of a parametric phase-insensitive copier followed by one or more PSAs. Broadband gain and noise performance of a fiber-based nondegenerate PSA has been characterized, both theoretically and experimentally. A record-low 1.1 dB noise figure was measured at >;26 dB gain, and a clear phase dependent gain was observed. Moreover, potential applications including phase noise squeezing and ultralow noise, multichannel and modulation-format-transparent linear amplification with up to 6 dB link noise figure advantage over conventional EDFA-amplified links have been experimentally demonstrated. The prospects and practical challenges of this intriguing amplification technology are also discussed.

IEEE Journal of Selected Topics in Quantum ElectronicsDec 7, 2011122 citations

Modeling and measurement of the noise figure of a cascaded non-degenerate phase-sensitive parametric amplifier

Zhi Tong, Adonis Bogris, Carl Lundström +4 more

Semi-classical noise characteristics are derived for the cascade of a non-degenerate phase-insensitive (PI) and a phase-sensitive (PS) fiber optical parametric amplifier (FOPA). The analysis is proved to be consistent with the quantum theory under the large-photon number assumption. Based on this, we show that the noise figure (NF) of the PS-FOPA at the second stage can be obtained via relative-intensity-noise (RIN) subtraction method after averaging the signal and idler NFs. Negative signal and idler NFs are measured, and <2 dB NF at >16 dB PS gain is estimated when considering the combined signal and idler input, which is believed to be the lowest measured NF of a non-degenerate PS amplifier to this date. The limitation of the RIN subtraction method attributed to pump transferred noise and Raman phonon induced noise is also discussed.

Optics ExpressJun 28, 201061 citations

Gain characteristics of a frequency nondegenerate phase-sensitive fiber-optic parametric amplifier with phase self-stabilized input

Renyong Tang, Jacob Lasri, Preetpaul S. Devgan +3 more

We experimentally demonstrate, for the first time to our knowledge, a phase-sensitive amplifier based on frequency nondegenerate parametric amplification in optical fiber, where the input signal-idler pair is prepared all-optically. Using two fiber-optic parametric amplifier sections separated by a fiber-based wavelength-dependent phase shifter, we observe and investigate phase-sensitive gain profile in the 1550 nm region both experimentally and theoretically. The realized scheme automatically generates gain-defining phase that is environmentally stable, making it advantageous for building phase-sensitive transmission links.

Optics ExpressJan 1, 2005127 citations

Generalised expression of the noise figure of phase sensitive amplifiers for an arbitrary number of modes

Yousra Bouasria, Debanuj Chatterjee, Fabienne Goldfarb +2 more

Abstract Phase sensitive amplifiers (PSA), contrary to usual phase insensitive amplifiers (PIA), are in principle capable to achieve noiseless amplification, i.e. exhibit a quantum-limited noise figure (NF) of 0 db. When implemented using four-wave mixing (FWM) in a non-linear fibre, extra waves can be generated by undesired FWM processes, which may introduce extra input ports for vacuum fluctuations, thus potentially degrading the NF. In this situation, we give here a general analytical quantum derivation of the PSA NF, valid for an arbitrary number of nonlinearly coupled modes. This expression is usable as soon as a linear input-output relation can be found for the annihilation and creation operators of the involved modes. It predicts that the noise level depends on the number of interacting waves. We illustrate the usefulness of this expression in the case of six waves, corresponding to four interacting quantum modes. In this example the signal NF is degraded by 0.4 db, compared to 10 db obtained for PIA operation of the same scheme.

arXiv:2012.09031Journal of OpticsDec 15, 20201 citation

Phase sensitive parametric amplifiers and their applications

Joseph Kakande

Phase sensitive amplification (PSA) is a remarkably powerful tool if implemented correctly - it allows amplification with a noise figure lower than quantum mechanics normally dictates, and also allows the development of systems that coherently process the phase of their optical inputs. PSA at infrared wavelengths can be achieved using second or third order optical nonlinearities - indeed the first demonstrations of PSA utilised degenerate three photon mixing in bulk crystals, allowing the observation of effects such as quantum quadrature squeezing. This PhD research project was aimed at translating the fascinating science of PSAs into applications, based on Kerr nonlinearity in optical fibres, capable of being deployed in modern core optical networks runnning at 40 Gbit/s and higher. This objective was an integral part of the European Union FP7 project PHASORS. Studies, both theoretical and experimental, were carried out on wideband non-degenerate PSAs. The inline cascaded fiber optic parametric amplifier (FOPA), in which a first phase insensitive FOPA is used to generate phase locked signal-idler pairs, followed by a second FOPA in which PSA takes place, was used to experimentally demonstrate PSA gain characteristics in linear and saturated modes of operation, with PSA obtained over 20 nm in the telecom C-band. Focus was then re-directed towards applying a dual pump PSA to DPSK regeneration. The amplitude and phase limiting characteristics of these devices were experimentally studied, in particular revealing that amplitude saturation arises due to an interplay between input phase and nonlinear phase matching along the nonlinear fibre. This feature was used to identify a regime of operation for DPSK regeneration combining simultaneous phase and amplitude regeneration. A practical DPSK regenerator based on a degenerate dual pump phase sensitive FOPA was built. The device advanced the state of the art by incorporating a pump synthesis stage that allowed black-box operation. Detailed measurements using noise sources with varying frequency distributions in both amplitude and in phase, are presented, and the ability of the system to improve the phase and amplitude characteristics of signals at its input was verified. Also presented are results showing the regenerator installed in the middle of an 800 km dark fiber link. Finally, a novel scheme was proposed and demonstrated that utilised parametric mixing to perform arbitrary phase quantization. This relied on the coherent addition of an M-level PSK signal with a conjugated (M-1)th phase harmonic, scaled by a coefficient m, to achieve M-level phase quantization. The concept was successfully demonstrated with QPSK data signals at 56 Gbaud, as well as used to quantize lower bandwidth test signals from 2 to 6 phase levels.

Mar 1, 20123 citations

Phase sensitive amplification with noise figure below the 3 dB quantum limit using CW pumped PPLN waveguide

Masaki Asobe, Takeshi Umeki, Osamu Tadanaga

The noise figure (NF) of a phase sensitive amplifier (PSA) based on a periodically poled LiNbO3 (PPLN) waveguide was evaluated in the optical and electrical domains. Phase sensitive amplification was realized using degenerate parametric amplification in the PPLN waveguide, which was pumped by the second harmonic frequency of the signal. Second harmonic pumping enables direct observation of the intrinsic amplified spontaneous emission (ASE), which determined the NF of the PSA. An NF below the 3 dB quantum limit was obtained by observing the intrinsic ASE. The low NF was also confirmed via the noise floor measurement of a cascaded PSA and erbium doped fiber amplifier in the electrical domain. The PSA was used as a preamplifier for detecting a 40 Gbit/s phase shift keying signal. The low noise characteristics were confirmed by the improved sensitivity.

Optics ExpressMay 25, 201260 citations