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.
Quanta Tech 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).