In this article, the RIE process has been improved, a
polymer arrayed waveguide grating (AWG) multiplexer with flat spectral response have been designed and fabricated using FPE polymer materials. Using the steam‐redissolution technique, the insertion loss and the crosstalk have been reduced. Experimental results show that the central wavelength is 1550.86 nm, and 3‐dB bandwidth is about 0.478 nm, insertion loss is 10.5 dB, crosstalk is about −20.5 dB. The insertion loss of an AWG device is reduced by about 3 dB for the central channel and 4.5 dB for the edge channels, and the crosstalk is reduced by 1.5 dB after the steam‐redissolution. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2199–2201, 2013