In the wonderful world of optoelectronics, the acousto-optic effect is a fascinating phenomenon, especially when it is applied in the 2000nm band, it opens a new door for many cutting-edge technologies. Today, let's talk about the realization principle of the acousto-optic effect in the 2000nm band and how the related devices are designed.
First of all, we have to understand what the acousto-optic effect is. Simply put, the acousto-optic effect is that when ultrasound propagates in a medium, the refractive index of the medium will change periodically, just like forming a "dynamic grating". When the laser is incident on this "grating", diffraction and other phenomena will occur, thereby modulating the light, such as changing the intensity and frequency of the light. This is like a regular ups and downs (changes in refractive index caused by ultrasound) suddenly appear on a flat road (uniform medium). When the light passes here, it will change the propagation state with the "ups and downs".
So how is the acousto-optic effect realized in the 2000nm band? This has to start with the choice of medium. For light in the 2000nm band, to find a suitable acousto-optic medium, its acousto-optic quality factor, transparency, etc. must be considered. Some crystal materials, for example, absorb less light in the 2000nm band and can efficiently produce refractive index changes through ultrasound, making them ideal choices. These media are like a "stage" specially prepared for light in the 2000nm band, allowing the acousto-optic effect to be performed brilliantly.
From a theoretical perspective, to accurately describe the acousto-optic effect in the 2000nm band, the relevant theory of acousto-optic interaction must be used. This involves the mathematical relationship between the wavelength of light, the frequency of ultrasound, and the acousto-optic parameters of the medium. For example, the frequency change of diffracted light is related to the frequency of ultrasound. By controlling the frequency of ultrasound and other parameters, the frequency of light in the 2000nm band can be accurately controlled, which is very useful in the fields of laser radar, optical communication, etc. This process can be imagined as a "music performance", where light and ultrasound are different "notes", and through clever "arrangement" (theoretical calculation and parameter control), the "melody" we need (light of specific frequency and intensity) can be played.
Next, let's look at device design. Taking the 2000nm fiber AOM (acousto-optic modulator) series as an example, there are many factors to consider when designing. First, look at the characteristic requirements, such as short response time, low insertion loss, high extinction ratio, etc. In order to achieve a short response time, the design of the acousto-optic medium and transducer must be optimized. The transducer is responsible for converting electrical signals into ultrasonic waves, just like a "translator", converting the "language" of electricity into the "language" of ultrasonic waves. A well-designed transducer can complete the conversion quickly and efficiently, allowing the entire device to respond quickly to the modulation of light.
Low insertion loss is also critical. This requires perfect coupling between the optical fiber and the acousto-optic medium to reduce the loss of light during transmission. The coupling of optical fiber and medium can be imagined as the connection of a water pipe. If the interface is not smooth, water will leak out (light loss), so the coupling structure must be carefully designed to allow light to pass "smoothly" through the acousto-optic modulation area.
From the parameter table, we can see the differences in parameters such as insertion loss, rise time, frequency shift, etc. of different models (such as SGTF80-2000-1P, etc.). These differences are designed according to different application scenarios. For example, in Q-switched fiber laser applications, devices with specific frequency shift and response time may be required to achieve precise control of laser pulses, just like equipping the laser with a "precision regulator" to make the laser output meet the required pulse form.
In terms of high-temperature stability and reliability, the device adopts an all-metal structure and compact sealed packaging. The all-metal structure is like putting on a layer of "solid armor" for the device, which can remain stable in harsh environments such as high temperature and prevent the internal acoustic-optical interaction from being "disordered". The compact sealed package can prevent the intrusion of external dust, moisture, etc., and ensure the long-term and reliable operation of the device, which is very important for equipment that continues to operate in industrial and scientific research environments.
In short, the realization of the acoustic-optical effect in the 2000nm band is the result of the close combination of theory and practice. Starting from the basic principles of the acousto-optic effect, selecting the right medium, making precise theoretical calculations, and then fine-tuning various performances during device design, each step is related to the final application effect. These 2000nm acousto-optic modulation devices are quietly shining in the fields of Q-switched fiber lasers, laser Doppler coherent applications, etc., driving optoelectronic technology forward. In the future, they will surely shine in more emerging fields. Let us look forward to more surprises from them!