High peak power Q-switched Er:YAG laser with two polarizers and its ablation performance for hard dental tissues

Abstract

An electro-optically Q-switched high-energy Er:YAG laser with two polarizers is proposed. By using two Al(2)O(3) polarizing plates and a LiNbO(3) crystal with Brewster angle, the polarization efficiency is significantly improved. As a result, 226 mJ pulse energy with 62 ns pulse width is achieved at the repetition rate of 3 Hz, the corresponding peak power is 3.6 MW. To our knowledge, such a high peak power has not been reported in literature. With our designed laser, in-vitro teeth were irradiated under Q-switched and free-running modes. Results of a laser ablation experiment on hard dental tissue with the high-peak-power laser demonstrates that the Q-switched Er:YAG laser has higher ablation precision and less thermal damage than the free-running Er:YAG laser.

A redshifted photonic bandgap and wide-angle polarization selection in an all-hyperbolic-metamaterial one-dimensional photonic crystal

“…Such a wide-angle polarizer would be useful in liquid crystal displays, 65 quantum interferometers, 66 and Q-switched lasers. 67 This paper is organized as follows. In Section 2, we illustrate the physical mechanism of redshifted PBGs in all-HMM 1-D PhCs based on the Bragg scattering theory.…”

“…Such a wide-angle polarizer would be useful in liquid crystal displays, 65 quantum interferometers, 66 and Q -switched lasers. 67…”

Effect of <i>Q</i>-switched Er:YAG laser irradiation on bonding performance to dentin surface

“…Such conditions expose the irradiated and surrounding tissues to thermal damages 17,21) , requiring the application of water cooling spray during laser use. The recently introduced Q-switched lasers are characterized by high peak power and a short pulse width (up to 100 ns) that can avoid the thermal damage, maintaining the benefits of conventional Er:YAG laser 16,22) . In particular, from recently conducted studies, it emerged that Q-switched laser, used at a relatively low power density, is able to selectively ablate affected dentine, showing an optimal cutting performance, without tissue overheating 16,22) .…”

“…The recently introduced Q-switched lasers are characterized by high peak power and a short pulse width (up to 100 ns) that can avoid the thermal damage, maintaining the benefits of conventional Er:YAG laser 16,22) . In particular, from recently conducted studies, it emerged that Q-switched laser, used at a relatively low power density, is able to selectively ablate affected dentine, showing an optimal cutting performance, without tissue overheating 16,22) . Nevertheless, the effects of Q-switched laser irradiation are not completely known.…”

Frequency-tunable wide-angle polarization selection with a graphene-based anisotropic epsilon-near-zero metamaterial

“…In the past decades, polarization selection has attracted researchers' great interest since its applications in liquid crystal display [1,2], read-write magneto-optical data storage [3], Q-switched lasing [4], and chiral molecule detection [5]. A typical physical mechanism to realize polarization selection is the Brewster effect [6].…”