A stabilised fibre-optic Mach-Zehnder interferometer filter using an independent stabilisation light source

We have demonstrated a stabilised scheme of fibre-optic Mach-Zehnder interferometer-type optical filter for application in periodic wavelength dividing filters. The stabilised scheme is based on controlling one arm length of the interferometer with electronically fedback fibre stretcher and utilizes an independent control light source and a voltage amplifier. This filter turns out to be useful for optical inputs not only of discrete spectra but also of broadband spectra. The output characteristics including stability, extinction ratio and transmission period are discussed.