# Training Videos

## Guided-wave acousto-optic devices

This is a continuation from the previous tutorial - acousto-optic tunable filters. Guided-wave acousto-optic devices are developed along the same principles discussed in the previous tutorials for bulk devices. For the same reasons as those that require practical bulk acousto-optic devices to be of Bragg type, all practical guided-wave acousto-optic devices also function in the Bragg regime. With only a few exceptions, a bulk counterpart can be identified for each guided-wave acousto-optic device, both of which have the same basic operation principles and are subject to the same considerations in terms of performance characteristics. Guided-wave acousto-optic devices differ from bulk...

## Acousto-optic tunable filters

This is a continuation from the previous tutorial - acousto-optic deflectors. An optical grating can be used for the separation or filtering of optical frequencies, as is seen in any grating spectrometer and in s distributed Bragg reflector as discussed in the grating waveguide couplers tutorial. It is also possible to use the index grating generated by an acoustic wave in a medium for such purposes. One advantage of such an acousto-optic filter, or acousto-optic spectrometer, is that it is electronically tunable because the period of the acousto-optic grating can be varied by altering the acoustic frequency. This electronic tunability...

## Acousto-Optic Deflectors

This is a continuation from the previous tutorial - acousto-optic modulators. The acoustic wave of an acousto-optic deflector is frequency modulated. Unlike an acousto-optic modulator, which is an amplitude modulator, an acousto-optic deflector is a frequency modulator, which allows its acoustic frequency to be varied electronically. Acousto-optic deflectors have many applications. A frequency shifter, which has the sole purpose of generating a diffracted optical beam at an optical frequency shifted by the amount of the acoustic frequency from the input optical frequency, can be considered as the simplest form of an acousto-optic deflector. Acousto-optic deflectors are also used in such...

This is a continuation from the previous tutorial - photoelastic effect. We see from the preceding two tutorials that the space- and time-dependent periodic permittivity changes induced by a traveling plane acoustic wave of the form given in (8-1) [refer to the elastic waves tutorial] can be generally expressed as $\tag{8-34}\Delta\boldsymbol{\epsilon}=\Delta\tilde{\boldsymbol{\epsilon}}\sin(\mathbf{K}\cdot\mathbf{r}-\Omega{t})$ where $$\mathbf{K}$$ depends on both the polarization and the propagation direction of the acoustic wave. In general, $$\Delta\tilde{\boldsymbol{\epsilon}}$$ is a function of the strain and the rotation generated by the acoustic wave in the medium, the elasto-optic coefficients of the medium, the mode and direction of the acoustic wave,...