Measurement of facet reflectivity of antireflection-coated electroabsorption modulator using induced photocurrent

A new method to measure the facet reflectivity of an antireflection (AR)-co ated electroabsorption (EA) modulator in the region of operating wavelength s is proposed. First, by measuring induced photocurrent and reflectance sim ultaneously at the front facet of an EA waveguide, the cleaved facet reflec tivity and propagation loss are determined. After coating the facet with AR , the residual reflectivity of AR-coated facet is obtained from the measure d photocurrent spectra and the predetermined facet reflectivity. We demonst rate the reflectivity of a double- layer AR-coated EA modulator can be meas ured to be similar to4 X 10(-4) at 1.55 mum for TE polarization by using th e proposed technique.