Study Of Broadband Optical Parametric Chirped Pulse Amplification

The optical parametric chirped pulse amplification was born in the early 1990s. Because of its unique advantages in the amplification of ultra short laser, great attention was paid after it was proposed for the first time. Several advantages make it one of the most important amplification techniques in ultra short laser, which are very high gain per single pass, high proportion of signal to noise, low thermal effects and high amplified signal beam quality.The optical parametric chirped pulse amplifiers can amplify the ultra short laser, while the optical parametric amplifiers should provide enough gain bandwidth accordingly. In this paper, we set a simulation model, which can simulate the optical parametric chirped pulse amplification pumped by non-homochromatic light or diverged beams. We also studied the impact of divergence angle, bandwidth and angularly dispersion of the pump on the gain and the gain bandwidth of optical parametric chirped pulse amplification. According to all kinds of effect, several methods and advices are proposed to improve the gain bandwidth of optical parametric chirped pulse amplification. These methods are very useful instruction to produce higher intensity and shorter pulses. The outline and innovation of this paper as follow:1). We retrospect the fundamental, advantages and progress of optical parametric amplification and optical parametric chirped pulsed amplification.2). Several techniques of broadband phase matched are introduced, including non-collinear optical parametric amplification, broadband phase matched with angularly dispersed beams, two beams pumped optical parametric amplifier and so on.3). A new scheme of optical parametric amplification is proposed to improve the gain band width, which is optical parametric amplification pumped with diverged beams. Several gain curves are simulated when the pump is non-diffraction limit Gaussian beam or beam of rectangular distribution in spatial spectrum respectively,using the method of Fourier transform and the fourth-order Runge-Kutta Algorithm.The results show that the gain bandwidth of optical parametric chirped pulse amplification can be obviously improved using diverged pump beam, either in the visible or in the near infrared. Very high gain and broadband spectrum can be obtained if the divergence angle and intensity of the pump is selected properly.4). In the system of Optical parametric chirped pulse amplification pumped with non-homochromatic light, impact of the bandwidth and the angularly dispersion of pump light on the gain and the gain bandwidth of the optical parametric amplification are theoretically studied. We decompose the pump which is not homochromatic into spectral components by use of the method of Fourier transform, then set a numerical model to resolve the three wave coupled function. From the numerical model and result of the three waves coupled function we can analyze impact of the bandwidth of pump light on the gain and the gain bandwidth of the optical parametric amplification. The results show that broadband pump light can also improve the gain bandwidth of the optical parametric amplification obviously.