Optical modulation of transmission lines using picosecond optoelectronic techniques

Optical pulse energy controlled delay in the propagation time of electrical picosecond pulses in YBa₂Cu₃O_7-x (YBCO) superconducting transmission lines has been investigated by using picosecond optoelectronic techniques. The transmission lines are microstrip lines on LaAlO₃ substrates and are illuminated by the frequency doubled output (532 nm) of a Nd:YAG laser. The propagation time of picosecond electrical pulses through the transmission lines was measured using electrical autocorrelation techniques with optical switches. By varying the optical pulse energy from 0 to 83 pJ the delay through the lines was tuned by 40 psec at 30 K. The propagation time shows a quadratic dependence on the optical pulse energy. As the optical pulse energy increases a gradual increase in pulse width was observed