Superconducting versus optical interconnections

Summary form only given. The authors contrast the results of work on long (30 cm) YBaCuO microstrip interconnections and short (<10 cm) waveguided optical interconnections. 4000-AA YBaCuO films were coevaporated on 1-in² LaGaO₃ substrates and a 30-cm microstrip was patterned by lift-off. Measurements suggest (1) that flux motion does not introduce significant nonlinearities below 76 K, (2) that J_c rather than H_c is the appropriate limit on maximum current density, and (3) that high-performance transmission lines can be achieved if the low surface resistance expected for superconductors is achieved. The authors have also evaluated an alkyl-silicon polymer waveguide material in which the waveguide is defined simply by exposure to deep ultraviolet, requiring no etching or other patterning of the material. Attenuations less than 0.5 dB/cm were measured on 1-cm waveguides, and low loss bends (1-mm radius) and single-plane crossovers were demonstrated. The optical interconnects formed are directly compatible with underlying electronics and optoelectronics and suitable for lengths of up to several centimeters (limited by attenuation).