定义：
该装置可以操控光束的性质，例如光功率或者相位
光调制器通常用来操控光束的性质，例如激光光束。调制器根据所调制光束的性质被称为强度调制器，相位调制器，偏振调制器，空间光调制器等。不同类型的调制器可以应用到不同的应用领域，例如光纤通信领域，显示设备中，调Q或者锁模激光器，以及光学测量中。
光调制器类型
存在几种不同的调制器类型：
- 声光调制器是基于声光效应的调制器。它们被用于切换或者持续调整激光光束的振幅，改变光频率，或者改变空间方向。
- 电光调制器利用的是泡克尔斯盒中的电光效应。它们可以调制偏振状态，相位或者光束功率，或者用于超短脉冲放大器一节中提到的脉冲提取。
- 电吸收调制器是一种强度调制器，用于光纤通信中的数据发射器上。
- 干涉调制器，例如马赫-曾德尔调制器，通常在光数据传输中的光子集成电路中采用。
- 光纤调制器可以基于多种原理。可以是真正的光纤器件，或者也可以是包含光纤尾纤的体元件。
- 液晶调制器适宜于应用到光学显示设备或者脉冲整形器中。它们也可以当做空间光调制器来使用，也就是说传输随空间变化，这可以用到显示设备中。
- 调制盘可以周期性的改变光束的功率，这在一些特定的光学测量中（例如采用锁定放大器）会用到。
- 微机械调制器（微机械系统，MEMS），例如硅基光阀和二维反射镜阵列尤其在投影显示中非常重要。
- 体光学调制器，例如电光调制器，可以采用很大的光束面积也可以应用于大功率的情况。而光纤耦合的调制器，通常是具有光纤尾纤的波导调制器，则易于集成到光纤系统中。
Definition: devices allowing one to manipulate properties of light beams, such as the optical power or phase
More specific terms: acousto-optic modulators, electro-optic modulators, Pockels cells, electroabsorption modulators, liquid crystal modulators, intensity modulators, phase modulators
An optical modulator is a device which can be used for manipulating a property of light – often of an optical beam, e.g. a laser beam. Depending on which property of light is controlled, modulators are called intensity modulators, phase modulators, polarization modulators, spatial light modulators, etc.
A wide range of optical modulators are used in very different application areas, such as in optical fiber communications, displays, for active Q switching or mode locking of lasers, and in optical metrology.
Types of Optical Modulators
There are very different kinds of optical modulators:
- Acousto-optic modulators are based on the acousto-optic effect. They are used for switching or continuously adjusting the amplitude of a laser beam, for shifting its optical frequency, or its spatial direction.
- Electro-optic modulators exploit the electro-optic effect in a Pockels cell. They can be used for modifying the polarization, phase or power of a beam, or for pulse picking in the context of ultrashort pulse amplifiers.
- Plasmonic modulators are a special type of electro-optic modulators which exploit the formation of plasmons (a special type of electromagnetic excitation) at metal surfaces, which lead to surface plasmon polaritons (SPPs). They can be extremely fast while having a low energy consumption.
- Electroabsorption modulators are semiconductor-based intensity modulators, used e.g. for data transmitters in optical fiber communications.
- Interferometric modulators, e.g. Mach–Zehnder modulators, are mostly exploiting the electro-optic effect in conjunction with interference. They are often realized in photonic integrated circuits for optical data transmission.
- Liquid crystal modulators are suitable for, e.g., optical displays and ultrafast pulse shapers. They are also available as spatial light modulators, i.e. with a spatially varying transmission, e.g. for displays.
- Micromechanical modulators (which are microelectromechanical systems = MEMS), e.g. silicon-based light valves and two-dimensional mirror arrays, are particularly useful for projection displays.
- Chopper wheels can periodically switch the optical power of a light beam, as required for certain optical measurements (e.g. those using a lock-in amplifier), and may thus be considered as optical modulators in a wider sense. Of course, that kind of device cannot provide arbitrary modulation controlled with an electrical input signal.
Bulk-optical modulators, e.g. of the electro-optic type, can be used with large beam areas, and handle correspondingly large optical powers. On the other hand, there are fiber-coupled modulators, often realized as a waveguide modulator with fiber pigtails, which can easily be integrated into fiber-optic systems.
