High resolution tunable optical filter

摘要

A high-resolution tunable optical filter uses a dispersive element in a double pass configuration. The double pass configuration is provided by a reflective quarter-wave plate that conveniently reduces polarization dispersion loss (PDL) of the filter. The filter also includes a fibre tube for supporting an input optical fibre and an output optical fibre, and a lens having an optical axis, which is disposed such that a focal point thereof is substantially at one of the input and output optical fibres. To provide increase resolution the filter is tuned by rotating the reflective quarter-wave plate. To provide high power capabilities the fibre jackets of the input and output fibres are optionally stripped back. To provide a symmetrical spectral response the fibre tube is optionally mounted at an angle to the optical axis of the lens.