High power performance of ultrahigh bandwidth MSM TWPDs

Low-temperature-grown GaAs (LTG-GaAs) based photodetectors (PDs) merit a lot of attention due to their ultrahigh electrical bandwidth performance. By utilizing photomixing technique, these high speed PDs can radiate power in the THz frequency regime. In such application, these PDs usually need to experience high optical power illumination and operate in high bias voltage. In this paper, we studied the behavior of a novel MSM traveling wave photodetector (MSM TWPD) under high optical power illumination and high bias level by electrical-optical sampling technique based on a femtosecond Ti:sapphire laser. This novel device has been demonstrated with ultrahigh bandwidth (570 GHz) and reasonable quantum efficiency (8%). With a large photoabsorption volume and better capability of undertaking high bias voltage, improved high power performance can also be obtained in this device compared with previous LTG-GaAs based p-i-n TWPD.