Chapter 6 Fiber Grating Band-Pass Filters Let the band pass. . . . For many applications, the transmission characteristics of a fiber Bragg grating are really the wrong way around: it is a band-stop rather than a band-pass filter. For example, tuning a radio enables the selection of a channel, not the rejection of it from a broad frequency spectrum. However, a Bragg grating works quite in reverse, and therefore cannot be easily used for channel selection. Optical trans- mission systems also require a "channel-dropping" function, in which a channel is selected from a large spectrum of designated channels. These optical channels are on a coarse grid of 100 GHz (multiples and submultiples of), which is cur-