Experimental Generation Of Non-Classical Optical Fields At1.3μm-Telecommunication Wavelength

With the rapidly development of modern science and technology, it requires operating the optical information and sensitivity in precise optical measurement are more and more strict. Shot noise limit has already given a critical limitation on treatments and measurements for the signal, which would block us to realize the objective world further. Simultaneously, with the power of signal reduces, the ratio of shot noise and incident light will raise relevantly, and the measurement of super-weak signal and improvements for signal-to-noise ratio are limited concequently.Since we have got the squeezed states of light in experiment, human obtains the light field with low noise that even lower than shot noise limit. Because that traditional light field could never have the quantum characteristics those of optical squeezed state, researches and applications about squeezed state are widely concerned. Requirements about long-distance transmission for the squeezed state of light result from improvement of practical application of quantum communication. Optical fiber is an ideal transmission medium, so, researches on non-classical light that based on fiber window with low loss at communications band (1.3μm,1.5μm) expand in the experiment. Previous investigations are mainly about1.5μm band because of its lowest transmission loss in fiber. And works of experimental preparation for squeezed field at the other communications band1.3μm are seldom. However, the optical squeezed state on the1.3μm window of communication has the advantage of smaller dispersion in fiber in contrast with the1.5μm band. Hence, we have carried out experimental preparation for squeezed field with1.3μm band, and preliminary analysed the influence of optical fiber transmission for squeezed field via measurement results of in the frequency domain and time domain, which lays the foundation for building a practical quantum networks and broadening the scope of application of squeezed state of light.Main works of this paper contain as follows: (1) Take our home-made all-solid-state intra-cavity frequency-doubled single-frequency Nd:YVO4/LBO laser as the pump source, and pump the optical parametric oscillator(OPO) based on a quasi-type-I phase-matched PPKTP crystal, who works below the threshold. Then we gain a optical vacuum squeezed state with quadrature amplitude, whose squeezed noise measured in experiment is lower than shot noise limit by6.1dB±0.1dB.(2) Coupling the transmission squeezed light from the optical parametric oscillator(OPO) and local oscillator light into the fiber with a indirect coupling way through the battery of lenses respectively. Then measuring the squeezed light field of coupled into the fiber before and after separately by a balanced homodyne detection. The squeezed state is transmitted100m in the fiber. Finally, we have discussed the effect of transmission process of the squeezed light field to its quantum properties in the optical fiber, then have reconstructed the Wigner function of the squeezed state of light field by quantum tomography method, and have analyzed differences between the Wigner function of light field of coupled into the fiber before and after.