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Abstract:

It is expected that the operation of microwave Kinetic Inductance Travelling Wave Parametric Amplifiers (KITWPAs) can be extended to the millimetre (mm) and the sub-mm wavelength range as long as the frequency is below the gap frequency of the superconducting film. This paper presents possible mm-wave designs for KITWPAs based on microstrip transmission lines. Our device is designed based on the BCS (Bardeen-Cooper-Schrieffer) model which successfully reproduces the measured transmission profile, gain, bandwidth, and nonlinear response of a fabricated KITWPA operating in the Ka-band, and includes the millimetre-wave dielectric loss determined by fitting the quality factor of a Wband microstrip resonator. We suggest a layout for a KITWPA operating near 220 GHz that can be fabricated using the same superconducting properties as the Ka-band device and can be coupled to a waveguide system. We conclude the paper by extending the 220 GHz design to higher frequency regimes approaching 1 THz.

Abstract:

Local oscillator sources have become a major technological deficit approaching the terahertz frequencies. For applications, where a narrow linewidth is necessary, such as coherent remote sensing, the best solution to signal generation is frequency multiplication, where phase locking can be easily achieved using the fundamental source. We present an alternative to existing frequency multiplier technologies for cryogenic applications. The device is a superconducting waveguide that has kinetic inductance dependent on the rf current through the device. The nonlinear kinetic inductance is anomalous to a nonlinear optical medium, where the Kerr effect causes 3- or 4-wave mixing, as demonstrated in microwave parametric amplifiers utilizing the same nonlinear effect. In 4-wave mixing, three photons at the fundamental frequency are mixed to generate a single photon at the third harmonic. Dispersion engineering is used to achieve wideband phase matching and phase out harmonics higher than the third. The device length is designed to be the point where most photons are up-converted to the third harmonic. Simulations of these devices lead to expected efficiencies as high as 90%. We report results from a NbTiN frequency multiplier from 34.2 to 104 GHz with efficiency better than 50%.

Abstract:

We describe a method for calculating the embedding impedance of an SIS mixer employing twin junction tuning. Calculation of the embedding impedance is done using equivalent transmission line circuits of the mixer, the measured pumped and unpumped IV curves of the mixer chip and the Tucker theory expressions of the tunneling currents. Our simulation method does not require the individual IV curves of the two junctions.

Abstract:

The Heterdyne Spectrometer Instrument (HSI) is one of two instruments on the Far-IR Spectroscopy Space Telescope (FIRSST) proposal to NASA. It would be the first heterodyne array receiver in space and has 3 frequency bands, each containing two 5-pixel arrays, one per polarizations. HSI uses high TRL (>6) components and is an innovative, but low-risk instrument.