Title :
Apodized fiber gratings for DWDM using variable efficiency phase masks
Author :
Singh, H. ; Morey, W.W.
Author_Institution :
3M Bragg Grating Technols., Bloomfield, CT, USA
Abstract :
Of the various applications of fiber Bragg gratings, their use as spectral filters is perhaps the most common. While the most important reasons why Bragg gratings are preferred over interference filters are cited as low insertion loss and polarization insensitivity, an often overlooked, but very important feature of Bragg gratings is the control over filter profile. Bragg gratings can easily be designed to have high or low reflectance, narrow or wide bandwidth, and none or any chirp. All these features make Bragg gratings a very attractive filter for DWDM applications such as channel multiplexing/demultiplexing or channel add/drop. While most requirements for DWDM applications such as low PDL, low insertion loss and low PMD are usually met by Bragg gratings, high channel isolation due to narrow bandwidth gratings is still a topic of investigation. The lower limit on the bandwidth is usually imposed by the existence of side lobes found in any grating filter. While it is well known that narrow bandwidth gratings can be achieved simply by apodizing the grating, a simple apodization yields a self induced chirp leading to resonance on the blue side of the filter. Strasser et al. (1996) reported that such effects can be eliminated by raising the average index of the grating such that it is constant along the grating. This phenomenon is illustrated using simulation tools.
Keywords :
chirp modulation; demultiplexing equipment; diffraction gratings; multiplexing equipment; optical fibre filters; phase shifting masks; wavelength division multiplexing; DWDM; apodized fiber gratings; channel add; channel demultiplexing; channel drop; channel multiplexing; chirp; fiber Bragg gratings; filter profile; high channel isolation; high reflectance; low insertion loss; low reflectance; narrow bandwidth; narrow bandwidth gratings; polarization insensitivity; self induced chirp; side lobes; spectral filters; variable efficiency phase masks; wide bandwidth; Bandwidth; Bragg gratings; Chirp; Fiber gratings; Filters; Insertion loss; Interference; Optical fiber polarization; Reflectivity; Wavelength division multiplexing;
Conference_Titel :
Vertical-Cavity Lasers, Technologies for a Global Information Infrastructure, WDM Components Technology, Advanced Semiconductor Lasers and Applications, Gallium Nitride Materials, Processing, and Devi
Conference_Location :
Montreal, Que., Canada
Print_ISBN :
0-7803-3891-X
DOI :
10.1109/LEOSST.1997.619184