Passive mode locking of a diode-pumped hybrid neodymium:glass and neodymium:yttrium orthovanadate lasers

In this thesis, I present the first experimental results of the passive mode locking of diode pumped hybrid Nd:glass and Nd:YVO₄ lasers with weakly and strongly inhomogeneously broadened laser media: Nd:phosphate glass or Nd:silicate glass, respectively. The spectral and temporal characteristics of the mode-locked hybrid lasers are studied in term of the pump ratio and the gain peak separation of the two hybrid laser media. The mode-locked hybrid laser performance and behavior can be explained by using unsaturated and saturated gain profile in the free running state. The gain profile of the hybrid laser is controlled by the Nd:YVO₄ gain via gain combination and cross saturated gain. To verify the accuracy of the numerical results, the cw hybrid laser experiment is conducted. Both simulation and experimental results show that, in both free running state and mode locking state, the spectral component of a hybrid laser is controlled by the Nd:YVO₄ gain. With a proper pump of Nd:YVO₄, the saturated gain profile of the hybrid laser is wider than that of Nd:glass laser. Un-smooth and narrower gain profile results by an excessive pump at Nd:YVO₄. The gain narrowing effect is magnified when gain peaks of hybrid laser are overlap. Un-smooth and narrow gain profile increase mode locking instability and produce longer pulses. In the picosecond regime, the pulse duration is limited by recovery time of the saturable absorber. In the picosecond regime, the hybrid Nd:phosphate glass and Nd:YVO₄ laser can mode lock at either 1054 nm or 1064 nm. Because of the soliton mechanism, the pulses can be generated in the femtosecond regime. With a strong soliton force, the wider and flatter gain profile of the hybrid laser can be utilized. The improvement of the hybrid laser performance is enhanced with a smaller negative GVD and strong pump power of Nd:glass media. In the femtosecond regime, the hybrid Nd:silicate glass and Nd:YVO ₄ laser generates a shorter pulse duration and better stability than the Nd:silicate glass alone.