KNI-MDL Seminar

Cryogenic Microwave Amplifiers for Quantum Computing and Radio Astronomy–Sander Weinreb, Caltech

Caltech has supplied over 1000 cryogenic low noise amplifiers to a multitude of   world-wide research institutions during the past several years.  These amplifiers are used on many radio telescopes for observations of objects such as the cosmic background, molecular lines, galaxies, stars, pulsars, and black holes. More recently the amplifiers are being used in quantum electronics research to sense the state of a superconducting cubit.  This talk will be tutorial and will discuss the sources of noise in microwave devices and systems, the types of semiconductors that are used, and the transistor cryogenic noise models which are used in the amplifier design. Examples of amplifiers and the systems requiring the amplifiers will be presented.

Advanced Schotty Diode Based Devices and Silicon Micromachining for Next Generation Ultra-Compact Terahertz Frontends-Jose V. Siles, JPL 

In the submillimeter-wave range, Schottky devices are by far the preferred technology as local oscillator sources and mixers of terahertz heterodyne instruments for long-term planetary mission where cryogenic cooling is not an option. Schottky based components have been successfully flown in different missions (MIRO on Rosetta, MLS on Aura, HIFI on Herschel). The outstanding scientific findings resulting from the observations made with these instruments is now driving a next generation of instruments with extended capabilities and increased performance. Next generation frontends need to be compact, lightweight, high-performance, multi-color multi-pixel, low-power and yet more sensitive than anything that has flown before.  This will be a game-changing advancement and will allow terahertz components or instruments to be part of every astrophysics and planetary science mission, providing a tremendous return on investment in the shape of science data. The objective of this talk is to discuss the state-of-the-art Schottky diode technology and the most recent technological developments introduced in order to accomplish these goals.

One of the major advances has been the introduction of the silicon micro-machining, which uses DRIE techniques to machine waveguide blocks with lithographic precision. Instead of packaging one chip at a time, silicon micromachining "bonds" all chips together to provide a robust, extremely powerful way of making terahertz receivers. Hence, an ultra-compact front-end can be achieved with lower overall losses and x50 times reduction in mass and volume.

To increase the power handling capabilities of Schottky devices and reduce waveguide losses to improve the overall performance of future terahertz sources, we have also recently developed a new frequency multiplier technology known as on-chip power combining, which consists of placing four multiplying structures within a single chip. The concept uses the vertical stacking capabilities of silicon micromachining to place the device perpendicularly to the input/output waveguides. Moreover, employing more accurate device models and better optimization techniques has allowed us to increase considerably the performance of Schottky devices in the recent years. We have developed the first room-temperature fully Schottky diode based receiver at 1.2 THz with world record performance. We also have demonstrated SOA performances of Schottky multiplied sources up to 2.7 THz, and almost one order of magnitude improvement is expected in the next years with the incorporation of some of the new concepts discussed herein. We are currently working towards the demonstration of the first all-solid state room-temperature local oscillator source at 4.7 THz.