定义：
基于阵列波导的光学滤波器或者复用器件。

阵列波导光栅（通常为光纤耦合的）可以将信号中不同波长的组分分开或合束。它通常为一个平面光波导，光从入射光纤首先进入多模波导中，然后通过一些单模波导后再次进入多模波导区域，最终进入输出光纤中。波长滤波是利用了干涉效应和单模波导中的不同光程差：即任何在单模波导中传播的频率组分和所有这些组分叠加后在任意信道上的输出光之间。任意输入端口和输出端口之间的结合得到的与波长相关的流量引起相移也与波长相关。 

图1：阵列波导光栅的结构图。 
尤其是具有很多通道的AWGs，需要非常精准的制作过程才能实现很低的通道间串扰。 
AWGs在不同材料系统中都能实现，例如，采用二氧化硅（SiO2），铟磷（InP）或者硅（Si）。 

应用 
阵列波导光栅主要应用于光纤通信系统中，尤其是利用波分复用器（WDM）的多路传输系统，需要将单个波长的信道合在一起或者分开。它可以是复杂光子集成回路的一部分，例如用作WDM数据发射器。阵列波导光栅还可以分离超连续光源光谱中的单个波长，或者用作超短脉冲的脉冲整形器。

Acronym: AWG

Definition: optical filter or multiplexer devices based on arrays of waveguides

More general term: optical filters

An arrayed waveguide grating is a (typically fiber-coupled) device which can separate or combine signals with different wavelengths. It is usually built as part of a planar lightwave circuit (or photonic integrated circuit), where the light coming from an input fiber first enters a multimode waveguide section, then propagates through several single-mode waveguides to a second multimode section, and finally into the output ports. Wavelength filtering is based on an interference effect and the different optical path lengths in the single-mode waveguides: any frequency component of the input propagates through all single-mode waveguides, and the output in any channel results from the superposition (interference) of all these contributions. The wavelength-dependent phase shifts lead to a wavelength-dependent overall throughput for any combination of an input port and an output port.

Figure 1: Structure of an arrayed waveguide grating.

Particularly for AWGs with large numbers of channels, a high precision of the fabrication is required for achieving a low channel cross-talk.

AWGs can be realized with different material systems, e.g. based on fused silica (SiO₂), indium phosphide (InP), or silicon (Si).

Applications

Arrayed waveguide gratings are mainly applied in optical fiber communication systems, in particular in those based on multi-channel transmission with wavelength division multiplexing (WDM), where individual wavelength channels must be combined or separated. They can be part of more complex photonic integrated circuits, functioning e.g. as WDM data transmitters. An arrayed waveguide grating may also be used for separating the lines in the optical spectrum of a supercontinuum source, or in a pulse shaper for ultrashort pulses.

Bibliography