Grafen ve karbon nanotüp doyabilen soğurucular ile çok yansımalı kovuklu femtosaniye kip-kilitli katı-hal lazerinin enerjisinin ölçeklendirilmesi

In mode-locking applications, single-walled carbon nanotube saturable absorbers (SWCNT-SAs) and graphene saturable absorbers (graphene-SAs) have emerged as important alternatives to semiconductor saturable absorber mirrors (SESAMs) due to their favorable optical characteristics, low cost, and relatively simple fabrication scheme. Therefore, it is of great interest to explore the limits of energy scaling in lasers mode-locked with SWCNT-SAs and graphene-SAs.In this thesis work, due to their unique wavelength range for biomedical applications, a room-temperature Cr4+: forsterite laser operating near 1.3 ?m was used in the mode-locking experiments. By incorporating a q-preserving multi-pass cavity (MPC) extension to the short x-cavity, an effective optical path length of ~ 60 m was obtained and the repetition rate of the pulses was reduced to 4.51 MHz from 144 MHz. In addition, by using double chirped (DCM) and Gires-Tournois interferometer (GTI) mirrors, nonlinear phase distortions due to self phase modulation were compensated to generate solitary femtosecond pulses. Furthermore, the power efficiency of different laser resonator architectures containing the graphene-SA or SWCNT-SA was investigated.The Cr4+: forsterite laser, mode-locked with a SWCNT-SA produced 121-fs pulses with 10-nJ pulse energy and 84-kW peak power at the wavelength of 1247 nm. The mode-locked spectrum had a width of 16 nm, corresponding to a time-bandwidth product of 0.37. Hence, the pulses were nearly transform-limited with a temporal profile of sech2.For graphene-SA mode-locking experiments, graphene samples with different number of layers were fabricated and characterized. The Cr4+: forsterite laser mode-locked with a single layer graphene-SA produced 96-fs pulses with 5.3-nJ pulse energy and 55-kW peak power at 1252 nm. In this case, the mode-locked spectrum had a width of 18.2 nm and the measured time-bandwidth product came to 0.33, also indicating that nearly transform limited solitary pulses were generated.To our knowledge, both of the results report the highest peak powers obtained to date from a femtosecond solid-state bulk laser mode locked by using SWCNT-SA and graphene-SA. Limitations to energy scaling were further explored during the experiments.