Genişletilmiş darbeli yükselticiler için femtosaniye Cr:ZnSe laserinin geliştirilmesi

In this thesis work, we describe the three main components of a chirped pulse amplifier (CPA). It is a technique in which nano-joule pulse energies of femtosecond lasers are amplified to micro-joule or milli-joule levels. In particular, the seed laser was experimentally constructed and the numerical design of the stretcher and compressor was completed. The seed laser is a continuous-wave, Kerr-lens mode-locked femtosecond Cr2+:ZnSe laser pumped by a 1800-nm thulium fiber laser. The astigmatically compensated, asymmetric x-cavity contained a 2.4-mm-long Cr2+:ZnSe sample with a pump absorption coefficient of 11.6 cm-1, and it was terminated with a 1% output coupler. Dispersion compensation was achieved by using a MgF2 prism pair. During Kerr-lens mode-locked operation, the laser generated 95-fs pulses at a pulse repetition rate of 94.3 MHz and with 40 mW of output power. The center wavelength of the pulses was 2.42 ?m. The pulses had a spectral width of 69 nm and a time-bandwidth product of 0.335, which is close to the transform limit for hyperbolic secant shaped pulses. In addition, by using the soliton area theorem, the nonlinear refractive index was estimated as 1.4x10-14 cm2/W for Cr2+:ZnSe. The calculated value agrees well with what has been reported in the literature and it is almost 100 times larger than the nonlinear refractive index of sapphire. In the case of the stretcher and compressor design, based on our numerical calculations, the stretcher allows us to stretch 100fs pulses to 100ps by using a diffraction grating pair with a groove density of 300 grooves/mm and separation of 76 cm.