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* Modulators & Fixed Frequency Sfhifters
Acousto-optic modulators are used to vary and control laser beam intensity. A Bragg configuration gives a single first order output beam, which intensity is directly linked to the power of RF control signal. The rise time of the modulator is simply deduced by the necessary time for the acoustic wave to travel through the laser beam. For highest speeds the laser beam will be focused down, forming a beam waist as it passes through the modulator.

AA proposes a wide range of modulators with associated drivers. The set is optimized to offer the best performances (rise time, extinction ratio...) .The RF driver features all the necessary signal to drive the modulator (carrier frequency, amplifier...) with analog or digital input control. A low cost OEM version is proposed together with a complete laboratory version (BOX). The laboratory version is a versatile turn-key tool for fast set-up and allows the user to have AM capabilities from front panel (DC modulation) or from an external signal.
 
* Fixed and Variable Frequency Shifters
A frequency shifter uses the shift inherent in the acousto-optic interaction to up- or down-shift a laser’s frequency. Two kinds of shifters can be distinguished: the fixed frequency shifter, and the variable frequency shifter. The frequency shift is directly equal to the RF frequency applied onto the transducer (we must not forget that the out put angle is also linked to the frequency : see deflectors).

Various techniques can be used to shift the laser beam, such as multiple travels inside the shifter to double or triple the frequency shift, or a combination of two frequency shifters to achieve low amount of shift (DC to KHz).

These devices can be used, for example, in optical heterodyning and interferometric applications, or in laser Doppler velocimetry for particle velocity analysis in sprays.
 
* Acousto-optic Tunable Filters
An AOTF is a solid-state, electronically tunable bandpass filter, which uses the acousto-optic interaction inside an anisotropic medium. These filters can be used with multi-lines sources (mixed gas lasers, Laser diodes...) or with broadband light sources (Xenon, Halogen lamps...). They allow to select and transmit a single wavelength from the incoming light.

The main advantage of this technique is the total absence of any moving part which lead sto a reliable, stable and fast technique for wavelength tuning. The RF frequency applied on the AOTF transducer controls the transmitted (filtered in 1st order) wavelength. A complete spectrum analysis can be done by varying the frequency corresponding to the wavelength range. The RF amplitude level applied on the transducer allows to adjust the transmitted (filtered) light intensity level. This is a unique feature that can provide the AOTF. It is fast (several μs), accurate and procures high extinction ratio.

AA proposes a whole range of AOTFs based on TeO2 with shear acoustic mode. The filters are designed so as to get the best performances in each wavelength range and to satisfy most of the applications: resolution down to 1 nm, Field of view up to 20 degrees, apertures up to 10 mm...In most cases, the filtered output from the tunable filter is made colinear to make easier the use of these devices, and to satisfy fiber pigtailing conditions. A random input polarization will be separated into two orthogonal polarizations (order -1 and +1).
 
* Q-Switches
A Q-Switch is a special modulator which introduces high repetition rate losses inside a laser cavity (typ 1 to 100 KHz).

They are designed for minimum insertion loss and to be able to withdtand very high laser powers. In normal use an RF signal is applied to diffract a portion of the laser cavity flux out of the cavity. This increases the cavity losses ans prevents from oscillation.

When the RF signal is switched off, the cavity losses decrease rapidly and an intense laser pulse evolves.
 
* Fiber Pigtailed
These fiber pigtailed devices can be used depending on the models as modulators, fixed frequency shifters or Q-switches.
Our standard versions are proposed with a single mode fiber with polarization maintaining, However on request, we can offer different types of fibers or connectors.
These devices are dedicated for telecommunication applications, as well as for printing, microscopy , Q-switching or any other application.