Acousto-Optic Tunable Filter (AOTF) | SIMTRUM Photonics Store

In practice, we also need an RF driver to excite the ultrasonic waves in the crystal through the RF driver, so as to achieve modulation and selective filtering of light. The frequency and intensity of the RF signal control the wavelength selection and performance of the filter, so RF driving is the key to achieving efficient, tunable filtering.

3.Calculation Formula:

The acousto-optical interaction can be described in terms of the Bragg diffraction condition. By adjusting the frequency of the RF signal, Λ can be altered, thereby enabling selective tuning of λ.

2Λsin(θ)=mλ

• Λ represents the wavelength of the sound wave
• θ denotes the angle between incident light and diffracted light
• m signifies the diffraction order
• λ refers to the wavelength of light 

Q: What is the input and output of AOTF fiber coupler head？

A: our AOTF both support free Space or fiber-coupled Input and output.

Q：Why use RF drivers?

A：Acoustic wave generation: AOTF works on the basis of the acousto-optic effect, in which sound waves produce periodic changes in the refractive index in the acousto-optic crystal. RF signals are converted into high-frequency sound waves that propagate through the crystal and form an acousto-optic front. RF drives are the primary means of generating these sound waves.

Wavelength adjustment: The frequency of the RF signal determines the frequency of the sound wave, which affects the refractive index period in the acousto-optic crystal. By adjusting the frequency of the RF signal, the wavelength of the light can be precisely controlled and selected.

Fast response: The RF driver enables fast adjustment of the AOTF for applications that require dynamic wavelength selection.

Q：Is it possible to use other types of drives?

A：Ultrasonic drive: In some special cases, low-frequency ultrasound can also be used for acousto-optic crystals, but this is usually not as efficient as RF signals. Ultrasound waves are less frequent, resulting in potentially larger devices, slower adjustment speeds, and higher material requirements.

Other wave methods: While RF driving is the most common and widely used method, theoretically, any acoustic wave generation method capable of producing periodic refractive index changes in an acousto-optic crystal can be used. However, these methods may not have the efficiency, precision, and speed of regulation of RF drives.

Q：What are the main factors affecting the wavelength selectivity of AOTF ?

A：

1. Materials of acousto-optic crystals:

Acousto-optic effects：Different crystalline materials have different acousto-optic effects, which affect the modulation and selectivity of light. The acousto-optic coefficient of the material, such as the photoacoustic coupling coefficient, directly affects the performance of the filter.

Optical anisotropy: Some crystals are anisotropic and the propagation characteristics of light may differ in different directions, which can affect selectivity.

1. Sound Frequency：Frequency vs. wavelength：The frequency of the sound wave determines the modulation range and filter width of the light wavelength in the acousto-optic crystal. The higher the frequency of the sound wave, the greater the range of wavelength choices that can be achieved.
2. Sonic power：Power and efficiency: The power of the sound wave affects the intensity of the acousto-optic effect, which affects the selectivity and filtering accuracy of the AOTF. The right amount of power can improve the performance of a filter, but too much or too little power can lead to a decrease in performance.
3. Beam incidence angle：Angle of incidence and selectivity: The angle of incidence of the beam affects the interaction between the sound wave and the light wave, which in turn affects the wavelength selectivity of the filter. Different angles of incidence change the diffraction conditions of the light, which affects the filtering effect.

Q：What is the difference between AOM EOM and AOTF？

A: