Development of continuous wave and mode locked titanium sapphire laser

Abstract

A Ti:sapphire laser was developed based on self mode-locking technique using a 'Z' folded cavity. Diode pumped solid state laser Verdi 5 was used as a pumping source with fundamental wavelength of 532 nm (suitable for the absorption band in Ti:sapphire crystal). Laser cavity was aligned by a set of mirrors with a high reflectivity of 99.8% to reflect the beam within the range of 720 nm to 820 nm, and an output coupler with a 5% transmission. A pair of prism was employed to control the dispersion for producing femtosecond pulse. The pulse was initiated via an external perturbation. The stability of the laser was sustained by providing a water cooling system. The laser operated in two modes which are continuous wave mode (CW) and pulse mode with mode-locked (ML) mechanism. The maximum output power of the CW Ti:sapphire laser is 1.12 W corresponding to a pumping power of 5.5 W and the efficiency of 26%. The optimum average power of mode-locked Ti:sapphire laser is 577 mW corresponding to the same pumping power of 5.5 W and a lower efficiency of 18%. The frequency of mode-locked laser pulse obtained is 96.43 MHz. The spectrum of laser radiation is centered at 806.74 nm with a bandwidth of 22.37 nm at full width half maximum (FWHM). The pulse duration of the mode-locked Ti:Sapphire laser is 30.53 femtosecond.