Exploiting Ballistic Electrons in a Uni-Traveling Carrier Traveling Wave Photo-Detector for Efficient Generation of Sub-MM Waves

The Generation of microwave signals by heterodyning two optical signals has been demonstrated in the past. However, so far this approach is limited in bandwidth, power and efficiency. In this paper we present an analysis of optical heterodyning in the uni-traveling carrier traveling wave photo detector taking into account the effect of ballistic electrons. The analysis is validated by comparison to measurement of an existing device made at the University of California, San Diego. Based on the above analysis a new photodiode design is made, which is expected to have a bandwidth well into the sub-MM wave region. The device exploiting the ballistic electrons effect can reach a bandwidth 2-3 times larger compared to device using velocity-saturated electrons.