“…For any desired finesse , the transmission curve will have peaks when , where is an integer, with a peak value equal to (7) We shall define the insertion loss, , as the ratio of the optical power without and with the insertion of the optical filter at the peak transmission wavelength, , expressed in dB. Since an optical power is directly proportional to the square of the magnitude of the electric field, the insertion loss, expressed in dB, is given as It can also be seen from (2) that depends on , and .…”