Abstract
A novel LiNbO3 (lithium niobate, LN) electro-optic (EO) Q-switch that can independently operate in the pulse-on regime without the assistance of a quarter-wave plate (QWP) or analyzer was designed and demonstrated. By theoretical analysis and calculations, the proper orientation of the LN was determined to be θ = 1.7° and φ = ±45°, and the quarter-wave voltage was identical to that of a conventional LN EO Q-switch. Additionally, the possible influences caused by the small angular variation between the wave normal and optic axis were found to be negligible. To the best of our knowledge, this is the first time that a LN crystal has been (xztw)-1.2°/1.2°-cut and used successfully in a pulse-on cavity without using a QWP or analyzer. The performance of the novel Q-switched laser and its temperature dependence were verified to be almost identical to those of a conventional pulse-on LN EO Q-switched laser, which strongly demonstrates the practicability of our novel Q-switch. This novel Q-switch design enables a more compact, lossless and stable laser cavity, which is of great concern for engineering applications.
Highlights
Lasers with narrow pulse width and high peak power have attracted considerable attention because of their extensive applications in the fields of remote sensing, laser machining, environmental monitoring, medicine, etc.[1, 2]
RTP and LGS crystals are favorable for the application of high-repetition-rate EO Q-switching because of their large EO coefficients, high optical damage threshold, insolubility in air and absence of piezoelectric ringing[3], and remarkable results have been achieved
We have taken the value of δ1 to be 5π/2 and the transmission direction of the polarizer to be along the X axis; the dimensions of the LN crystal were 9 mm × 9 mm × 18.8 mm (X × Y × Z)
Summary
Lasers with narrow pulse width and high peak power have attracted considerable attention because of their extensive applications in the fields of remote sensing, laser machining, environmental monitoring, medicine, etc.[1, 2]. RTP and LGS crystals are favorable for the application of high-repetition-rate EO Q-switching because of their large EO coefficients, high optical damage threshold, insolubility in air and absence of piezoelectric ringing[3], and remarkable results have been achieved. LN crystals are nonhygroscopic, and they possess a low absorption coefficient and insert loss[19] They can operate stably in a wide temperature range[20], which makes LN crystals the main EO crystal applied in military applications. Previous reports on LN EO Q-switches have all adopted the configuration wherein an electric field is applied to the X or Y direction, and the light propagates parallel to the optic axis[17] These Q-switches mainly operate in two modes: pulse-off and pulse-on. The wave plate is well known to be very sensitive to temperature and stress[23], which increases the difficulty of clamping and debugging
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