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Theoretical and Experimental Investigation for the Generation of Non-classical Light at 1.5μm with Continuous Variables

Author: FengJinXia
Tutor: ZhangKuanShou
School: Shanxi University
Course: Optics
Keywords: Continuous variables 1.5μm Squeezed Quantum entanglement Frequency multiplication Optical parametric process
CLC: O431.2
Type: PhD thesis
Year: 2008
Downloads: 186
Quote: 3
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Abstract


In the past nearly five decades, significant progress in the study of quantum optics is one of the generation of non-classical light field and its research in the field of quantum information applications. Quantum information research originated in the single-particle separation of variables of the system, and later extended to infinite dimensional Hilbert space of continuous variable systems. Continuous variable quantum information with high detection efficiency, get a decisive struggle, the transmission bit rate and other advantages, it has aroused widespread interest in the study. In recent years, the use of continuous variable quantum entanglement has completed a decisive quantum cryptography, quantum dense coding and quantum entanglement swapping for continuous variables such as the important research areas of quantum communication principle experiment, the light source used, but are concentrated in 1.06μm and 1.08μm band. To achieve practical quantum communication systems that require non-classical light in optical fiber transmission, the wavelength of the transmission loss in the optical fiber is large, the quantum properties of particular its exponentially as the transmission distance. This would require non-classical light field band extends to the lowest loss optical fiber communication window-1.5μm. The continuous variables dissertation around 1.5μm wavelength optical communication generation of non-classical light field to carry out a series of theoretical and experimental research. Completed work includes the following aspects: 1) Preparation of a 1560nm high power CW single-frequency laser light source, and the use of confocal FP cavity weak feedback technology to improve the quality of light. We use single-frequency semiconductor laser as a seed source injected erbium-doped fiber amplifier technology, first obtain a high-power optical communication band continuous single-frequency laser source, as the band produced non-classical light field and the injection pump signal light field. Experimentally injected power 1mW in the seed source, the resulting maximum continuous output power of 2W single frequency 1560nm laser output. Since the inherent noise semiconductor laser and fiber amplifier spontaneous emission noise introduced other reasons, the output laser intensity noise and phase noise is much higher than the shot noise limit, we used confocal FP cavity weak feedback technology, narrowing the width of the light source and reduced light intensity noise and phase noise, for subsequent experiments provide a better light. 2) the use of quasi-phase-matched external-cavity frequency doubling crystal was highly 780nm laser source. First, the theoretical analysis of the conditions for optimum SHG efficiency and tolerance of each parameter, as an experimental study theoretical guidance. Pump source using the above 1560nm continuous single-frequency laser source pumped with a periodically poled lithium niobate crystal frequency cavity formed by the external cavity resonance frequency doubling technology, access to high-frequency 780nm laser output. When the pump when power is 960mw, 780nm laser output is 700mW, maximum SHG efficiency was 73%. Using lock-in amplifier technology and electronic servo system lock multiplier chamber, so that long-term stable operation of 780nm laser frequency. 3) the use of optical parametric process to obtain compression of 1.5μm continuous variables as 2.4dB squeezed vacuum. Parametric oscillator uses two mirrors standing wave cavity, the nonlinear crystal is periodically poled lithium niobate. Using 1560nm light field as the injected signal light field, 780nm light field as a pumping light field, through the threshold degenerate optical parametric oscillator gain 2.4dB compression degree of 1.5μm continuous variables squeezed vacuum states. And, in theory, numerical analysis and signal light field pumping optical field for additional noise generated squeezed light field compression effect. 4) theoretically designed using two single-mode squeezed field 1.5μm beam splitter coupled in 1.5μm entangled states acquire the theoretical model, numerical analysis of the pumping field as well as additional noise coupling process model mismatch for entangled states generated by the impact. In the experiment discussed technical issues to be solved, to generate continuous variable 1.5μm entangled states experimental study made adequate preparations. In the research work, an innovative work are the following: 1. Experimentally for the first time received a continuous variable 1.5μm optical communication band squeezed vacuum state. (2) the use of quasi-phase external-cavity frequency doubling crystal technology to obtain high efficiency 780nm continuous single-frequency laser source. 3 Use the seed source implant amplification technology and confocal FP cavity weak external cavity feedback technology, access high-power narrow-linewidth 1.5μm continuous single-frequency laser source. 4 studied theoretically 1.5μm entangled states generated during pumping extra noise and light field using a 50/50 beam splitter when generating entangled states entangled state mode mismatch field entanglement effects. In conclusion, this thesis to obtain a continuous high power 1560nm single-frequency laser source, based on the use of quasi-phase-matched crystals, through doubling and parametric process, carried out continuously variable optical communication wavelength (1560nm) with a squeezed light field and entangled states Field of theoretical and experimental studies for the further development of practical quantum information networks, quantum computers, and long-distance quantum communication foundation.

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CLC: > Mathematical sciences and chemical > Physics > Optics > The light nature of the theory > Quantum optics
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