Bruce D. Sinclair

A laser diode array pumped, Nd: YVO4/KTP, composite material microchip laser

Abstract Fifty milliwatts of green (532 nm) fundamental spatial mode light have been generated by a continuous wave, frequency doubled microchip laser, consisting of a 0.5 mm thick piece of Nd: YVO4 in intimate optical contact with a 2 mm thick piece of KTP, and pumped by a laser diode array immediately behind the microchip. The initially nominally plano/plano cavity produced a near diffraction limited fundamental output beam at all pump powers.

Guiding effects in Nd:YVO/sub 4/ microchip lasers operating well above threshold

Guiding of the transverse mode in Nd:YVO/sub 4/ microchip lasers is examined both experimentally and theoretically at pump powers well above threshold. It is found that thermal changes in the cavity geometry induced by intense diode pumping can be well understood using a simple model. However, an understanding of these effects is not sufficient to explain the nature of the transverse mode. Gain-related guiding effects are found to play an important role even at pump powers well above threshold. For a 0.5-mm-thick microchip laser, a difference of around 30% is observed between the minimum beam waist expected due to thermal guiding and the measured beam waist. The gain-related effects are described theoretically and their importance is demonstrated experimentally.

Pump power induced cavity stability in lithium neodymium tetraphosphate (LNP) microchip lasers

Abstract Pump power induced deformation of the pumped surface of a 380 μm thick, lithium neodymium tetraphosphate (LNP) microchip laser has been studied and found to be the predominant mechanism involved in definition of the transverse mode of operation. Single frequency powers of up to 20 mW have been obtained from the LNP microchip by minimisation of the gain length within the material.

Microchip Nd:vanadate lasers at 1342 and 671 nm

As much as 105 mW of single-frequency output at 1342 nm was obtained from a diode-laser-pumped Nd:YVO(4) microchip laser. An intracavity frequency-doubled device generated 10 mW of single-frequency red radiation.

Two-photon effects in continuous-wave electromagnetically-induced transparency

Electromagnetically-induced transparency (EIT) in a cascade three-level scheme is studied in rubidium vapour using continuous-wave titanium sapphire lasers. A counter-propagating experimental configuration significantly reduces the coupling laser power requirements and a reduction in absorption of over 90% is observed. The hyperfine structure of the upper level is seen within the EIT feature and the application of EIT to high-resolution two-photon spectroscopy is discussed. Simultaneous measurements of the excitation to the upper state are presented and clearly show Autler-Townes splitting and power broadening.

Widely tunable all-solid-state optical parametric oscillator for the visible and near infrared.

An all-solid-state optical parametric oscillator (OPO) has been developed in which the signal and idler waves can be tuned over the ranges 455-665 and 760-1620 nm, respectively, with the potential for covering the entire range 420-2300 nm. The OPO uses a critical type I phase-matching geometry in lithium triborate and is pumped at 355 nm by frequency-tripled radiation from a diode-laser-pumped Nd:YAG laser. Oscillation thresholds (minimum 0.3 mJ), pump depletions (>35%), and linewidths of the OPO are reported.

Developing and evaluating animations for teaching quantum mechanics concepts

In this paper, we describe animations and animated visualizations for introductory and intermediate-level quantum mechanics instruction developed at the University of St Andrews. The animations aim to help students build mental representations of quantum mechanics concepts. They focus on known areas of student difficulty and misconceptions by including animated step-by-step explanations of key points. The animations are freely available, with additional resources available to instructors. We have investigated their educational effectiveness both in terms of student attitude and performance. Questionnaires showed that students are on the whole very positive about the animations and make substantial use of them. A diagnostic survey administered to level 2 and 3 students showed that level 2 students significantly outperformed level 3 students on topics which they had investigated using the animations.

Compact low-threshold Q-switched intracavity optical parametric oscillator

We report a singly resonant pulsed intracavity KTiOPO>(4) optical parametric oscillator that uses a semi-monolithic microchip laser design. The compact (50-mm-long), low-threshold (1.3-W) cavity uses a novel quadrupole deflector Q switch to give 4-microJ pulses at 1.064 microm and 0.4-microJ signal pulses of 5.6-ns duration at 1.53 microm with a repetition frequency of 5 kHz when it is pumped with a 2-W laser diode. The signal pulses are diffraction limited and single frequency.

Comparison of lithium triborate and β-barium borate as nonlinear media for optical parametric oscillators

We compare the relative merits of the new nonlinear materials β-barium borate and lithium triborate for use as gain media in singly resonant pulsed optical parametric oscillators pumped by either excimer lasers or frequency-upconverted diode-laser-pumped solid-state lasers. Lithium triborate is the material of choice when one requires low-pump-energy threshold devices ( 100 mJ) that are associated with excimer lasers.

Frequency-doubled microchip lasers

Microchip lasers with internal second harmonic generation allow the efficient generation of visible light from particularly compact and readily manufactured devices. This paper reviews the underlying physics of these devices, and points to some of the reasons for their success.