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A flash-lamp-pumped Er:Cr:YSGG laser at 2.79-microm wavelength has been acousto-optically Q switched. The Q-switched pulse energy and duration depend on pump pulse level and relative Q-switching time. Limits of single-pulse operation with the given acousto-optic diffraction efficiency have been determined. Resonator length, position of the Q switch, and output mirror reflectivity have been varied to obtain high pulse energy and the shortest pulse duration in the TEM00 transverse laser mode. A maximum single-pulse energy of 27 mJ and a minimum pulse duration of 120 ns were obtained with an output mirror reflectivity of approximately 25%. The highest Q-switched single-pulse energy amounted to 52% of the free-running, fundamental mode output pulse energy.

Er:YAG 2.94-microm lasers and Er:YLF 2.81-microm lasers were actively mode locked, with TeO(2) as the acousto-optic modulator. The Er:YLF crystal generated shorter and more stable pulses, whereas the Er:YAG had a higher slope efficiency of 0.8% in free-running operation. Mode-locked pulse durations of < 700 ps were obtained with Er: YLF by applying 4 W of electrical driving power to the LiNbO(3) transducer.

An interferometric scanning acoustooptic (AO) spectrum analyzer is described. The instantaneous detector array is replaced by an AO Bragg cell driven by a short rf pulse and a single fast photodetector, and the diffracted beam is mixed with a local oscillator. The temporal modulation of the heterodyne signal gives the spectrum of the input signal with linear characteristics. Using this architecture, a dynamic range of 70 dB can be achieved with a large time-bandwidth product (1000) and high speed (50 micros/spectrum).

An acoustooptic spectrum analyzer is described that is based on a new method of measuring spatial light intensity distribution in the Fourier plane. Instead of a detector array, an acoustooptic Bragg cell combined with a fast high dynamic range detector is used. With special driving signals, a time-bandwidth product of >1000, a speed of <50 micros/spectrum, and an increased dynamic range of >40 dB can be achieved.

Spatial distribution of coherent light intensity is measured with an acoustooptic Bragg cell. With step function or short pulse driving signals, the integral function of the spatial intensity distribution or the distribution itself appears at the time dependent output of a single detector. Speed, resolution, and dynamic range are comparable or better than these parameters of detector arrays.