Single passband microwave photonic filter with high selectivity and large tunable range

A tunable single passband microwave photonic filter with high selectivity and flexible tunability based on stimulated Brillouin scattering (SBS) is theoretically analyzed. The passband is generated due to phase to amplitude modulation conversion by mapping the Brillouin gain spectrum induced by SBS process. Typically the linewidth of Brillouin gain spectrum for a given fiber is a constant, which restricts the filtering performance in terms of selectivity. In order to alleviate this restriction, spectrum narrowing technique is applied to reduce filter bandwidth by superimposing the gain spectrum with two loss spectra. In addition, the technique based on gain-loss compensation is used to broaden the filter tunable range. In theory, near 60 % filter bandwidth reduction and maximum tuning range of 2νB\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$2\nu _{B}$$\end{document} are achieved.