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Phase-sensitive fiber amplifiers

Phase-sensitive amplifiers (PSAs) provide mutually reciprocal gains for the two orthogonal quadratures of input electric field: while one quadrature is amplified, the other is attenuated by the same amount. This property exempts them from the 3-dB noise-figure (NF) limit imposed by the quantum-mechanical uncertainty relations. In fact, an ideal PSA amplifies the noise by the same factor as the signal, thereby preserving the signal-to-noise ratio and exhibiting 0-dB NF. Hence, the PSAs can be used as noiseless amplifiers in the communications systems. In addition, their phase-sensitivity can be used to regenerate phase-modulated signals.

Experimentally, the PSAs can be realized by means of optical parametric amplification (OPA) in either c(2) (e.g., bulk crystals) or c(3) (e.g., highly-nonlinear fiber) materials. The description below refers to our work on fiber-based PSAs (our work on bulk-crystal-based PSAs is described here).

Prof. Vasilyev’s group, along with its collaborators, has the following experimental “claims to fame” in the field of fiber-based optical parametric amplifiers:

  • First optical fiber amplifier with sub-3-dB noise figure [1,2],
  • First phase-sensitive amplifier based on the non-degenerate four-wave mixing in fiber [3,4],
  • First multi-channel phase-sensitive fiber amplifier [5],
  • Lowest noise figure of any fiber amplifier (1.5 dB below the 3-dB quantum limit) [6,7].

In addition to the experimental demonstrations above, we laid out the pioneering architectures for non-degenerate phase-sensitive inline amplifiers [8] and amplified transmission links [3,5] that were subsequently successfully implemented by EU Project PHASORS (2008–2011, http://www.eu-phasors.eu/index.html) with spectacular field trials by University of Southhampton and Chalmers University [Nature Photon. 4, 690 (2010); ibid. 5, 430 (2011)].

Our current research activities in this area include development of amplifiers of multiple spatial modes for space-division multiplexing systems, using waveguide- or multimode-fiber-based OPA [9].

Selected publications

  1. D. Levandovsky, M. Vasilyev, and P. Kumar, “Amplitude squeezing of light by means of a phase-sensitive fiber parametric amplifier,” Opt. Lett. 24, 984–986 (1999).
  2. D. Levandovsky, M. Vasilyev, and P. Kumar, “Near-noiseless amplification of light by a phase-sensitive fibre amplifier,” PRAMANA-Journal of Physics 56, 281–285 (2001).
  3. M. Vasilyev, “Phase-sensitive amplification in optical fibers,” Frontiers in Optics / Laser Science XXI Meeting, October 2005, Tucson, AZ, invited paper FThB1.
  4. R. Tang, J. Lasri, P. S. Devgan, V. Grigoryan, P. Kumar, and M. Vasilyev, “Gain characteristics of a frequency nondegenerate phase-sensitive fiber-optic parametric amplifier with phase self-stabilized input,” Opt. Express 13, 10483–10493 (2005), http://www.opticsinfobase.org/abstract.cfm?URI=oe-13-26-10483 .
  5. R. Tang, P. S. Devgan, V. S. Grigoryan, P. Kumar, and M. Vasilyev, “In-line phase-sensitive amplification of multi-channel CW signals based on frequency nondegenerate four-wave-mixing in fiber,” Opt. Express 16, 9046–9053 (2008), http://www.opticsinfobase.org/abstract.cfm?URI=oe-16-12-9046 .
  6. Z. Tong, A. Bogris, C. Lundström, C. J. McKinstrie, M. Vasilyev, M. Karlsson, and P. A. Andrekson, “Modeling and measurement of the noise figure of a cascaded non-degenerate phase-sensitive parametric amplifier,” Opt. Express 18, 14820–14835 (2010), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-18-14-14820 .
  7. Z. Tong, C. Lundström, M. Karlsson, M. Vasilyev, and P. A. Andrekson, “Noise performance of a frequency non-degenerate phase-sensitive amplifier with un-equalized inputs,” Opt. Lett. 36, 722–724 (2011).
  8. M. Vasilyev, “Distributed phase-sensitive amplification,” Opt. Express 13, 7563–7571 (2005),
    http://www.opticsinfobase.org/abstract.cfm?URI=oe-13-19-7563 .
  9. M. Annamalai and M. Vasilyev, “Phase-sensitive multimode parametric amplification in a parabolic-index waveguide,” IEEE Photon. Technol. Lett. 24, 1949–1952 (2012).