Angle-tuned Fabry-Perot etalon filter having Gaussian transmittance curves

We present an angle-tuned Fabry-Perot etalon filter that has periodic Gaussian transmittance curves down to 40 dB from peak transmissions in spectral domain. This unique property becomes possible introducing an offset to the output-coupling fiber with respect to the incident Gaussian beam. This filter can be used not only as a general-purpose narrow bandwidth filter but also as an optical noise filter for wavelength-division multiplexed channels to eliminate the amplified-spontaneous emission or the back-scattered lights in bidirectional transmissions.