1,721,166 research outputs found
Nonlinear optics
No full textThere are two reasons for being interested in nonlinear optics. Does it tell us anything about the structure of materials? And secondly, can it be used in the production and handling of optical radiation? As an applied physicist it is the latter which principally interests me and in this article I will describe nonlinear devices which use the square law nonlinearity. These include harmonic generators, up-converters and down-converters, and parametric amplifiers and oscillators. First however, we must learn a little basic nonlinear optics
Tunable lasers
No full textThree ways have already been found of tuning lasers to emit light of particular wavelengths chosen from a wide range. This ability is rapidly extending the uses to which lasers can be pu
Intensity thresholds of optical parametric oscillations
No full textG.D.Boyd and D.A.Kleinman have published a comprehensive analysis of the 'Parametric Interaction of Focused Gaussian Light Beams' (Ref.1 hereinafter referred to as BK). In this paper they derived the 'optimum' focusing and 'optimum' crystal length which minimized the pump power, P required to achieve optical parametric oscillation (OPO) in a given system. This optimization has proved very valuable in obtaining OPO in the visible and near infra-red. (The first CW oscillator (ref.2) based on Ba2NaNb5O15 provides an excellent example of the application of BK power optimization)
Tunable infra-red down-conversion in silver thiogallate
No full textA ruby laser beam mixed in AgGaS2 with the output of various ruby-pumped dye lasers has provided downconverted infrared radiation tuned from 4.6 to 12µm. The measured phase-matching angles agree well with calculated values. Peak infrared powers of a few hundred milliwatts have been produced
Active Q-switch technique for producing high laser power in a single longitudinal mode
No full textA Pockels-cell Q switch has been operated in a manner analogous to a saturable absorber, thus allowing the simple and reliable selection of a single longitudinal mode. A TEMoo mode Nd-CaWO4 laser has produced 400kW pulses in a single longitudinal mode with a shot-to-shot frequency stability of about 0.01 /cm
Tunable medium infra-red generation in silver thiogallate by down-conversion of flash-pumped dye laser radiation
No full textThe outputs of flash-lamp pumped rhodamine 6G and rhodamine B lasers have been mixed in a AgGaS2 crystal. The generated difference-frequency radiation has been tuned from 8.7 to 11.6µm. Measurements of laser-induced damage of AgCaS2 have been made in the region of 600 nm which show a rapid fall in threshold with decreasing wavelength
Generation of tunable medium infra-red radiation by optical mixing in proustite
No full textThe outputs of a ruby laser and a tunable dye laser (pumped by the ruby laser) have been frequency-mixed in a proustite crystal. Difference wavelengths have been generated around 5 and 11 µm tuning being achieved for the latter covering the range 10.1 to 12.7 µm. Extrapolations from these preliminary results indicate that currently available lasers and nonlinear crystals should allow continuous tuning from 2.5 to 12.5 µm, with bandwidths substantially smaller than 0.1 /cm and at pulsed powers of the order of a kilo-watt
Single longitudinal mode selection of high power actively Q-switched lasers
No full textA Pockels cell Q-switch has been operated in a manner analogous to a saturable absorber by initially keeping the cell partly open for the first 1000 or so double passes and then opening it completely at a pre-set resonator power. This then allows simple and reliable selection of a single longitudinal mode. A detailed discussion is given of the design considerations which lead to the correct choice of mode-selecting device. With three different devices, a TEMoo mode Nd:CaWO4 laser has produced 400 kW pulses in a single longitudinal mode with a shot-to-shot frequency stability of ~ 0.01 /cm
7B1 - Ruby laser loss measurement by comparison of R1, R2 thresholds
No full textA simple method of measuring the losses of a ruby laser resonant cavity has been developed in which the thresholds for R1 line and R2 line operation are compared. A quartz birefringent filter is placed in the cavity with quartz disk cut to allow Brewster-angle operation and of such a thickness that the separation between pass bands of the filter analyzer combination is 2.8nm. The analyzer, placed between the filter and the output mirror, consists of a stack of fused quartz plates at the Brewster-angle. A known loss is introduced into the cavity by means of a plate inclined to the laser beam at a known angle. With the filter set for R2 operation the threshold is adjusted to a suitable value by rotating the loss plate to give an attenuation L2 pass. The filter is then reset for R1 operation and a different (larger) attenuation L1 must be introduced by the loss plate to raise the R1 threshold to the same level. An analysis of the threshold populations of the 2E levels shows that the losses of the cavity due to all sources of loss other than the loss plate may be obtained from a plot of log L1, against log L2
- …
