Research On High Space - Constrained Compact Optical Parameter Enlarging Imaging Technology

Optical parametric amplification(OPA) has been utilized in the field of image information since 1990 s. The unique advantages allow OPA imaging to be widely used in many fields, including biomedicine, physics, materials, laser radar, aeronautics and astronautics, military defense, and so on. OPA imaging for biological tissue can recognize its fine structures. OPA imaging can also improve greatly the resolution and sensitivity of laser radar. Ultrafast temporal gating of the wavelength-shift OPA imaging pumped by ultrashort laser pulses can be utilized to achieve high temporal resolved fluorescence lifetime imaging, while ultra-high pumping intensity allows the femtoseconds OPA imaging to have unprecedented spatial bandwidth. Additionally, optical parametric amplification can convert the infrared into visible imaging… Anyway, OPA imaging has presented its significance and promising applications.This thesis focuses on both experimental and theoretical stud ies of OPA imaging. Here we use ultrashort pulses as the pump, meanwhile, either stretched broadband source or a separated continuous-wave radiation has chosen as the signal. As a result, we have developed a novel design, which realizes simultaneously the noncritical phase- matching and elimination of spatial geometrical smearing, thereby improved the spatial resolution of the OPA imaging. Our work can be outlined as followings.The first part presents the theoretical analysis on optical parametric amplification from the three-wave coupling equations. The introduction includes the energy conversion, walk-off effect, acceptance angles and so on in the process of OPA. We not only analyze the phase matching conditions, but also discuss the gain and spatial bandwidth of the type-I and II non-collinear OPA using b-BBO as nonlinear crystal by numerical simulations.Then, we turn our attentions to OPA imaging. This part places emphases on the spatial gain and spatial bandwidth of the OPA imaging. After the discussion and comparison of the type-I and type-II non-collinear phase- matching of OPA, we find out a way to realize non-critical phase matching and to eliminate spatial geometrical smearing.Finally, the thesis presents a compact design for high-spatial-resolution OPA imaging, which is pumped by 400 nm ultrashort pulses, meanwhile, seeded by either a monochromatic CW beam or a broadband chirped pulses basing on type-I and II phase-matching. O ur results show that type-II OPA imaging has higher spatial resolution than the type-I. The imaging gain of type-II OPA imaging with 1064 nm signal is up to 104 while the two dimensional SBP for the idler image is about 74,000, which, to our acknowledge is the highest record reported up to date. Non-collinear Type-II OPA imaging with a separated monochromatic continuous wave as signal has its unique advantages, e.g. great flexibility to chose wavelength of the seed, no need of temporal synchronizer, simple configuration, and easiness to record signal. Besides, this design allows us to realize non-critical phase- matching and be free of spatial geometrical smearing, which increases the spatial bandwidth of the idler imaging.