Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Journal of Modern Optics

Signal Enhancement by Optical Amplification in Autocorrelation Measurements

Michael Harris, R. Loudon, Terence J. Shepherd, J. Michael Vaughan

Published Apr 1, 1991• 5 citations
Publisher

Abstract

The effect of optical amplification on the signal-to-noise ratio of autocorrelation measurements has been investigated experimentally. A light signal containing correlation information was amplified by an inverted population (phase-insensitive) optical amplifier. The data clearly show that the amplification may either degrade or enhance a subsequent autocorrelation measurement, depending on the experimental conditions. In particular, enhancement is possible when the detector quantum efficiency is low, or its noise is high. However, when all the signal photons are already being detected with no extra noise, then any optical amplification will inevitably lead to degradation of the data quality, due to addition of amplified spontaneous emission noise (ASE) from the amplifier itself.

DOI
10.1080/09500349114550631

Related papers

Principles of light amplification

Stefano Bottacchi

Introduction Most of the lightwave transmission systems operating today benefit fully from extensive deployment of optical amplifiers (OA). These components perform the amplification of optical intensity directly in the optical domain, without resorting to any electrical-domain regeneration. Optical amplifiers increase the average number of output photons per unit time by several orders of magnitude compared with the incoming signal intensity. However, as with every amplifying process, optical amplification cannot be achieved without paying back for the unavoidable noise power added to the signal intensity. As we will see in detail in Chapter 6, the optical amplification process comes with optical noise generated by spontaneous emission inside the active medium. The intensity of the optical signal is represented by the flux of the signal photon population. Conversely, the photons generated by the spontaneous emission process inside the optical cavity represent the noise photon population. The fundamental phenomenon supporting optical amplification is stimulated emission. The basic property of stimulated emission, making the great difference from spontaneous emission and enabling optical amplification, is the coherent nature of the photon generation process. Accordingly, both signal and noise photons go through the same multiplication process by means of stimulated emission. Unless the optical cavity where the stimulated emission takes place (the active cavity) presents selective features for enhancing the signal photon population relative to the spontaneous one, there is no way to avoid noise photons going through stimulated emission, filling most of the cavity population. As a consequence, both photon populations increase, leading respectively to amplified signal intensity and to amplified spontaneous emission intensity. It should be apparent that every noise photon can create a new identical noise photon as a result of stimulated emission, effectively increasing the noise intensity in the active optical cavity. This is the well-known mechanism of amplified spontaneous emission (ASE) noise in optical amplification. Any improvement in the optical amplifier structure devoted to increasing stimulated over spontaneous emission will probably increase the optical signal-to-noise ratio (OSNR) at the cavity output. The spectrum of gain characteristic of the optical active medium is usually wide enough to support an efficient amplification of the broadband spontaneous emission spectrum, leading to the broadband ASE noise power spectral density.

Cambridge University Press eBooks•Sep 6, 2014•0 citations

Reduction of signal-spontaneous noise in optical amplifiers

G. Du, Scott Roger Shepard, A. Wright

The beat between an amplified optical signal and the amplified spontaneous emission (ASE) noise is typically the primary limitation to the performance of optical fiber amplifiers. A filtering technique which might reduce this beat noise by 3dB creates a paradox since the noise figure's quantum limit of 3dB could then be reduced to 0dB implying noiseless amplification, which is impossible. The conjecture that this paradox might be resolved by different attenuations of the quantum and semiclassical descriptions of signal-spontaneous noise has been experimentally rejected . Herein, we present a variation of that experiment and telecommunication' applications of this filtering technique are discussed.

IEEE International Midwest Symposium on Circuits and Systems (MWSCAS)•Nov 11, 2002•0 citations

Laser-amplifier gain and noise

R. Loudon, Michael Harris, Terence J. Shepherd +1 more

A theoretical study is presented of the gain and the noise spectra of laser amplifiers at pumping rates both above and below the oscillation threshold. The theory is valid for both class-A and class-B laser systems, where the decay rate of the collective atomic dipole moment greatly exceeds the decay rates of the atomic population inversion and the laser cavity. The gain and the noise properties are shown to be strongly influenced by a four-wave mixing of the signal and image frequencies via a modulation of the population inversion. Particular attention is paid to the residual noise flux that persists in the laser output above threshold and to the typical characteristics of a second-order phase transition displayed by the gain in the threshold region. The results for the above-threshold laser amplifier are compared with experimental measurements of both gain and noise for the argon-ion (class-A) and ${\mathrm{CO}}_{2}$ (class-B) lasers. The signal-to-noise ratios for both heterodyne and direct-detection measurements are evaluated, and the conditions are determined under which optical amplification can lead to an enhancement of sensitivity.

Physical Review A•Jul 1, 1993•37 citations

Noise in optical amplifiers

Gianfranco Cariolaro, Roberto Corvaja, Pierluigi Franco +2 more

This article presents an application of a recently published probablistic model for traveling wave optical amplification. Both optical signal and amplified spontaneous emission (ASE) noise are modeled as bunches of photons traveling along the amplifying region with size varying according to simple random rules. The results of the theory enable one to obtain a complete and accurate characterization of the signal and noise counting at the amplifier output. On the basis of the above statistics, we find a realistic evaluation of the limits imposed by both quantum and ASE noise on the performances of a receiver including an optical amplifier at a preamplifier stage.

Fiber & Integrated Optics•Jan 1, 1994•2 citations

Quantum noise properties of a nonlinear amplifier

Roy S. Bondurant

We propose and analyze a nonlinear optical amplifier that is phase insensitive but has no additive noise. When the input field is in a coherent state, the noise figure is -6 dB when the gain is high. However, unlike conventional linear amplifiers with -3 dB noise figures, the detectibility of the amplified signal is not degraded. The amplifier is constructed simply, in principle, by the same type of nonlinear interferometer used in photon number quantum nondemolition measurements.

Physical Review Letters•Sep 13, 1993•4 citations

Amplified squeezed states: analyzing loss and phase noise

K M Kwan, M. J. Yap, Jiayi Qin +7 more

Abstract Phase-sensitive amplification of squeezed states is a technique to mitigate high detection loss, which is especially attractive at 2 µm wavelengths. We derived an analytical model proving that amplified squeezed states can mitigate phase noise significantly. Our model discloses two practical parameters: the effective measurable squeezing and the effective detection efficiency of amplified squeezed states. A realistic case study includes the dynamics of the gain-dependent impedance matching conditions of the amplifier. Our results recommend operating the optical parametric amplifier at high gains because of the signal-to-noise ratio’s robustness to phase noise. Amplified squeezed states are relevant in proposed gravitational wave detectors and interesting for applications in quantum systems degraded by the output coupling loss in optical waveguides.

arXiv:2401.04937•Classical and Quantum Gravity•Sep 18, 2024•6 citations
The effect of optical amplification on the signal-to-noise ratio of autocorrelation measurements has been investigated experimentally. A light signal containing correlation information was amplified by an inverted population (phase-insensitive) optical amplifier. The data clearly show that the amplification may either degrade or enhance a subsequent autocorrelation measurement, depending on the experimental conditions. In particular, enhancement is possible when the detector quantum efficiency is low, or its noise is high. However, when all the signal photons are already being detected with no extra noise, then any optical amplification will inevitably lead to degradation of the data quality, due to addition of amplified spontaneous emission noise (ASE) from the amplifier itself.
Introduction Most of the lightwave transmission systems operating today benefit fully from extensive deployment of optical amplifiers (OA). These components perform the amplification of optical intensity directly in the optical domain, without resorting to any electrical-domain regeneration. Optical amplifiers increase the average number of output photons per unit time by several orders of magnitude compared with the incoming signal intensity. However, as with every amplifying process, optical amplification cannot be achieved without paying back for the unavoidable noise power added to the signal intensity. As we will see in detail in Chapter 6, the optical amplification process comes with optical noise generated by spontaneous emission inside the active medium. The intensity of the optical signal is represented by the flux of the signal photon population. Conversely, the photons generated by the spontaneous emission process inside the optical cavity represent the noise photon population. The fundamental phenomenon supporting optical amplification is stimulated emission. The basic property of stimulated emission, making the great difference from spontaneous emission and enabling optical amplification, is the coherent nature of the photon generation process. Accordingly, both signal and noise photons go through the same multiplication process by means of stimulated emission. Unless the optical cavity where the stimulated emission takes place (the active cavity) presents selective features for enhancing the signal photon population relative to the spontaneous one, there is no way to avoid noise photons going through stimulated emission, filling most of the cavity population. As a consequence, both photon populations increase, leading respectively to amplified signal intensity and to amplified spontaneous emission intensity. It should be apparent that every noise photon can create a new identical noise photon as a result of stimulated emission, effectively increasing the noise intensity in the active optical cavity. This is the well-known mechanism of amplified spontaneous emission (ASE) noise in optical amplification. Any improvement in the optical amplifier structure devoted to increasing stimulated over spontaneous emission will probably increase the optical signal-to-noise ratio (OSNR) at the cavity output. The spectrum of gain characteristic of the optical active medium is usually wide enough to support an efficient amplification of the broadband spontaneous emission spectrum, leading to the broadband ASE noise power spectral density.
The beat between an amplified optical signal and the amplified spontaneous emission (ASE) noise is typically the primary limitation to the performance of optical fiber amplifiers. A filtering technique which might reduce this beat noise by 3dB creates a paradox since the noise figure's quantum limit of 3dB could then be reduced to 0dB implying noiseless amplification, which is impossible. The conjecture that this paradox might be resolved by different attenuations of the quantum and semiclassical descriptions of signal-spontaneous noise has been experimentally rejected . Herein, we present a variation of that experiment and telecommunication' applications of this filtering technique are discussed.
A theoretical study is presented of the gain and the noise spectra of laser amplifiers at pumping rates both above and below the oscillation threshold. The theory is valid for both class-A and class-B laser systems, where the decay rate of the collective atomic dipole moment greatly exceeds the decay rates of the atomic population inversion and the laser cavity. The gain and the noise properties are shown to be strongly influenced by a four-wave mixing of the signal and image frequencies via a modulation of the population inversion. Particular attention is paid to the residual noise flux that persists in the laser output above threshold and to the typical characteristics of a second-order phase transition displayed by the gain in the threshold region. The results for the above-threshold laser amplifier are compared with experimental measurements of both gain and noise for the argon-ion (class-A) and CO2{\mathrm{CO}}_{2}CO2​ (class-B) lasers. The signal-to-noise ratios for both heterodyne and direct-detection measurements are evaluated, and the conditions are determined under which optical amplification can lead to an enhancement of sensitivity.
This article presents an application of a recently published probablistic model for traveling wave optical amplification. Both optical signal and amplified spontaneous emission (ASE) noise are modeled as bunches of photons traveling along the amplifying region with size varying according to simple random rules. The results of the theory enable one to obtain a complete and accurate characterization of the signal and noise counting at the amplifier output. On the basis of the above statistics, we find a realistic evaluation of the limits imposed by both quantum and ASE noise on the performances of a receiver including an optical amplifier at a preamplifier stage.
Abstract Phase-sensitive amplification of squeezed states is a technique to mitigate high detection loss, which is especially attractive at 2 µm wavelengths. We derived an analytical model proving that amplified squeezed states can mitigate phase noise significantly. Our model discloses two practical parameters: the effective measurable squeezing and the effective detection efficiency of amplified squeezed states. A realistic case study includes the dynamics of the gain-dependent impedance matching conditions of the amplifier. Our results recommend operating the optical parametric amplifier at high gains because of the signal-to-noise ratio’s robustness to phase noise. Amplified squeezed states are relevant in proposed gravitational wave detectors and interesting for applications in quantum systems degraded by the output coupling loss in optical waveguides.