The Theoretical And Experimental Research On Optical Parametric Image Amplification

Recently, considerable attention has been paid to the optical parametric image amplification (OPIA) in the nonlinear optics and quantum optics. OPIA is of great significance for biomedicine, laser radar, optical remote sensing and ultrahigh-speed imaging and other fields. It open a new way to investigating quantum imaging and fluorescence dynamics. Optical parametric image amplification has been investigated theoretically and experimentally in this dissertation. The main contents are summarized as follows:1. The input-output relation of OPIA is analyzed and OPIA gain is discussed. Assuming that the input image is either still or change very slowly in time, at the condition of the broadband approximation (spatial frequencies bandwidth of OPIA more than the bandwidth of input image), we numerical simulate and calculate the gain profile of phase-sensitive amplification (PSA) and phase-insensitive amplification (PIA). Our analysis shows that the scheme work well with a broadband OPIA, which ensures that output image is a faithful copy of input image, with high fidelity, great gain and big image resolution. Relation between phase match and gain is discussed, when the phase match condition is perfectly fulfilled, in the broadband limit, input image is amplified effectively, which intensity is homogeneously distributed. The gain peak shifts to higher spatial frequencies and spatial bandwidth narrows, this effect occurs when a small phase mismatch is induced. As the magnitude of this mismatch is increased, OPIA could be used to selectively amplify the given spatial-frequency of the weak image.2. Quantum noise characteristic of OPIA have been investigated theoretically. Taking account to influence of the pixel area on noise figure, we obtain the qualification of noiseless amplified. The area of the pixel detector is more than imaging resolution and is much smaller than the smallest details of input image, noiseless amplification can be realized in the perfectly phase match condition or the phase mismatch condition. When the phase match condition is perfectly fulfilled, in the broadband limit, input image is noiseless amplified. However, the given spatial-frequency of the weak image is noiseless amplified, when a small phase mismatch is induced. Though this amplification is nonideal, by adjusting the phase mismatch condition, the spatial frequencies of input image can be noiseless amplified one by one.3. Parametric amplification of a monochromatic image has been investigated experimentally in type-I phase-matched BBO (b-BaB₂O₄) crystal at degeneracy. The weak image is amplified and the conjugate image is generated, and the different spatial frequencies of this image are amplified by the pump beam.4. Kilohertz (KHz) femtosecond (fs) OPIA has been investigated experimentally. The 400nm light pulse as pump light is obtained by the second-harmonic generation in 2mm BBO type-I crystal. The object was illuminated by the 800nm signal beam and imaged on the input face of 5mm length type-I phase-matched BBO crystal by the imaging system. By adjusting time delay between the signal pulse and pump pulse, the optical image can be amplified. The experiment provides an experimental basis for broadband fs OPIA when white-light continuum is the source of imaging.