Passband flattening of PHASAR WDM using input and output star couplers designed with two focal points

Abstract

We have presented and demonstrated a new method for flattening the passband of PHASAR channels. Input and output star couplers are designed with two focal points to produce two adjacent image points for each signal wavelength. An eight-channel-200-GHz PHASAR has been fabricated with a 0.5-dB passband equal to half the channel spacing.