Electro-optic modulator optimization for optically based passive millimeter-wave detection

Recent efforts in our group towards the fabrication of sensors capable of detecting passive levels of millimeter-wave radiation have led to the development of an optically-based detector with sub-picowatt noise equivalent powers. This sensor is based on upconverting the received radiation into sidebands on an optical carrier using electro-optic modulation techniques and, subsequently, suppressing the remaining carrier energy. The noise equivalent power of such detectors is critically dependent on the ability of the electro-optic modulator to efficiently convert frequencies up to and exceeding 95 GHz onto the optical carrier while suppressing potential noise sources. In this paper, we discuss the specific device requirements generated by this unique potential application of high-frequency optical modulators. The effects of various modulator properties, such as half-wave voltage, frequency response, and maximum optical power density are discussed in the context of millimeter-wave detection capability. In addition, we present experimental efforts towards fabricating a passive millimeter-wave detector based on this approach, including efforts to develop an optimized optical modulator technology.