Towards continuous-wave lasing emissions based on dyed-doped cholesteric liquid crystal templates

Abstract

This research aims to overcome the fatal shortcomings of traditional liquid crystal (LC) laser including photobleaching of dyes and induced thermal disturbance for moving towards the goal of continuous?-wave (CW) laser output The experiments are performed based on DDCLC and DDCLC template samples at various pump energies (50 ? 1000 ?J/pulse) and repetition rates (10 ? 10k Hz) at a long-termed excitation (one hour) Experimental results show that the lasing performances between the two lasers are different at regimes of low and high pump energies or repetition rates At a regime of low pump energy or repetition rate (? 700 nJ/pulse or ? 100 Hz) both the two lasers have less decay in lasing output and the lasing wavelength of the DDCLC template laser is more stable than that of DDCLC laser The results are attributable to the template-induced stabilization of optical resonator At a regime of high pump energy or repetition rate (> 700 ?J/pulse or >100 Hz) the lasing decay rate of DDCLC template laser is higher than that of DDCLC laser at identical pump condition and the recovering ability for the latter is better than the former The results are attributable to the nanoporous-template-induced suppression in exchange between bleached and non-bleached dyes Third the rotation method of the DDCLC template sample is employed for effectively reducing the excitation frequency such that the template laser can endure a high repetition rate of long-termed excitation up to 10000 Hz with less decay of lasing output Additionally the polymer matrix in the template can stabilize the DDLC in the nanopores by secondary force which provides enough centrifugal forces to the DDLC being thrown under the high-speed rotation even without any encapsulation processing In the future a potential application of a broadband tunable CW-like LC laser can be realized through the sample-rotating method

Date of Award	2020
Original language	English
Supervisor	Chia-Rong Lee (Supervisor)