Abstract
The main purpose of my thesis is the characterization of a THz photonic transmitter (PT) and its main component a near-ballistic uni-traveling-carrier photodiode by using electro optic (EO) sampling. Here, we constructed an EO sampling system primarily composed of a Mode Locked Er: doped Fiber Laser at 1.56m, a ZnTe EO crystal, polarizing optics and a balanced detector. In order to verify the performance of this system, we first measure the distribution of transverse and longitudinal electric fields on a coplanar waveguide (CPW). The results are in agreement with theoretically predicted field distribution using the conformal transformation. Secondly, we measured the waveform of comb generated picosecond electric pulses propagating on CPW, with a pulse width of about 110ps. Finally, we characterized the waveform of electric pulses generated by the Near-Ballistic Uni-Traveling-Carrier Photodiode. There were multi-reflection signals in time domain. In the frequency domain, we can see that there are two bands one is at 26.65GHz and the other one is near 80GHz. The former one corresponded to the period of multi-reflected spurious signal. The 80GHz band, on the other hand, is the designed output of the PT. Multiple reflections are tentatively attributed by the impedance mismatch of the measured setup. Considering the loading effect, measured EO response of the photodiode is consistent with the sub-THz (millimeter wave) signal radiated from the PT.