An all-fibre optical homodyne tomography apparatus is realized for reconstructing the photon statistics of the superposition between optical noise and signal. This apparatus is employed to measure the noise figure of an optical amplifier. (2 pages)
The recently developed method of optical homodyne tomography (OHT) allows one to obtain the photon statistics of a single mode with single-photon resolution. Recently, we used OHT to prove the Bose Einstein distribution (BED) character of parametric fluorescence. In general, in an OHT setup, a weak signal beam is mixed on a 50/50 beamsplitter with a strong local oscillator beam of the same polarization and spatio-temporal mode. In this paper, we apply OHT to show, we believe for the first time, that ASE noise of a single mode in an EDFA is Bose-Einstein distributed.
We measured the time-domain quantum statistics of a pulsed, high-repetition-rate optical field by balanced homodyne detection. The measuring apparatus discriminates the time scales on which intrinsic quantum fluctuations prevail from those scales for which technical noise is overwhelming. A tomographic reconstruction of weak coherent states with various average photon numbers demonstrates the potential ability of the system to measure high-repetition-rate, time-resolved signals. Possible extensions to other physical situations are discussed.
Optical homodyne tomography (OHT) is a tool that allows the reconstruction of Wigner functions for each detection frequency of a propagating optical beam. It can measure probability distribution functions (PDF's) of the field amplitude for any given quadrature of interest. We demonstrate OHT for a range of classical optical states with constant and time varying modulations and show the advantage of OHT over conventional homodyne detection. The OHT simultaneously determines the signal to noise ratio in both amplitude and phase quadratures. We show that highly non-Gaussian Wigner functions can be obtained from incoherent superpositions of optical states.
We report measurement of the photon-number distributions of zeros and ones that emerge from an erbium-doped fiber amplifier (EDFA) in an on-off modulated communication system. Single-mode single-photon resolution was achieved by employing the method of optical homodyne tomography. The measured distributions agree with the quantum predictions of a Bose-Einstein distribution for the zeros and a Laguerre (noncentral negative binomial) distribution for the ones over a dynamic range up to 40 dB. The resulting noise figure of the amplifier compares well to that measured by an optical spectrum analyzer.