We propose and experimentally demonstrate a novel and simple photonic microwave notch filter that uses a high-birefringent fiber that gives a fixed differential group delay (DGD), together with a DGD element that gives a tunable DGD. This configuration overcomes the problems of optical coherence interference and chromatic dispersion, which may occur in schemes that use fiber delay lines or fiber gratings. Also presented is a theoretical analysis for the performance of the microwave filter that uses the present configuration. The present scheme provides a continuous tuning capability for changing the notch frequency. Measured notch rejection is greater than 40 dB. This scheme can operate over a wide wavelength range of the optical carrier. There is good agreement between experiment results and theoretical analysis.
© 2005 Optical Society of America
G. X. Ning, S. Aditya, P. Shum, N. Liu, Y. D. Gong, and Chao Lu, "Tunable microwave filter that uses a high-birefringent fiber and a differential-group-delay element," J. Opt. Soc. Am. A 22, 913-916 (2005)