In a 1 × N wavelength division (de)multiplexer, N receiving (Rx-) gradient-index-rod lenses (GRIN’s) are connected to a common transmitting (Tx-) GRIN. All GRIN’s are a little longer (ΔZ0 for the Tx- and ΔZi with i = 1, 2, …, N for the Rx-GRIN’s) than the quarter-pitch. To reduce the average coupling loss and the deviations, ΔZ0 and ΔZi are optimized independently (unequally) or equally by computer programming for small N, such as N = 4 and 8. For a larger N (e.g., 16), a relay GRIN is required, which is a little (ΔZr) longer than the half-pitch. The best position of the relay GRIN is located between the seventh and the eighth Rx-GRIN’s. Other parameters including ΔZ0, ΔZi, and ΔZr are all optimized. As a result the (de)multiplexer has lower losses.
© 1998 Optical Society of America
(060.1810) Fiber optics and optical communications : Buffers, couplers, routers, switches, and multiplexers
(060.4230) Fiber optics and optical communications : Multiplexing
(110.2760) Imaging systems : Gradient-index lenses
(120.1680) Instrumentation, measurement, and metrology : Collimation
W. S. Hu, Q. J. Zeng, and Y. H. Jin, "Reduction of Coupling Loss in a One-to-many Collimating System for a Wavelength Division (de)Multiplexer," Appl. Opt. 37, 4084-4090 (1998)