Design and characterisation of terahertz Schottky diode harmonic mixers
Licentiatavhandling, 2021

Efficient, compact, and reliable terahertz frequency converters preferably operating at ambient temperature are crucial for stabilising far-infrared optical sources. This thesis focuses on the design and characterisation of terahertz Schottky diode harmonic mixers for frequency stabilisation of quantum-cascade lasers.
First, the influence of idler terminations on harmonic mixer performance and diode embedding impedance at radio and local oscillator frequencies was
studied. Based on this, a 3.5-THz, ×6-harmonic mixer was designed. A planar, single-ended Schottky diode with a sub-µm contact area was realised on a
2-µm suspended GaAs substrate. The integrated mixer circuit was assembled in an E-plane split-block with the aid of beam leads. The Schottky diode anode pad was designed to act as a radio frequency E-plane probe and extended as a beamlead to provide dc ground, resulting in an electrically compact circuit. The design was validated by conducting a sensitivity analysis of critical parameters that are susceptible to fabrication tolerances. Two integrated circuits with Schottky contact areas of 0.11 and 0.14 µm2 were assembled on mixer modules and dc/RF characterisation was carried out. Both harmonic
mixers exhibited a conversion loss of about 60 dB at an intermediate frequency of 200 MHz. When evaluated in a phase-locked loop, it resulted in a
signal-to-noise ratio of 40 dB, which was more than sufficient to phase lock the quantum-cascade lasers.
This work presents uncooled, efficient THz harmonic mixers for stabilising THz optical sources. It opens up many opportunities for building a THz heterodyne spectrometer with a high spectral resolution to detect gas species such as hydroxyl radical and atomic oxygen in the frequency range of 3-5 THz.

Frequency converters

Terahertz electronics

Phase locking

Schottky diodes

Heterodyne receivers

Harmonic mixers

Frequency stabilisation

Kollektorn A423
Opponent: Dr. Jeffrey Hesler, CTO, Virginia Diodes Inc. (VDI), USA

Författare

Divya Jayasankar

Chalmers, Mikroteknologi och nanovetenskap (MC2), Terahertz- och millimetervågsteknik

RISE Research Institutes of Sweden

Gigahertzcentrum

Effect of idler terminations on the conversion loss for THz Schottky diode harmonic mixers

International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz,; Vol. 2019-September(2019)

Paper i proceeding

A 3.5-THz, x6-Harmonic, Single-Ended Schottky Diode Mixer for Frequency Stabilization of Quantum-Cascade Lasers

IEEE Transactions on Terahertz Science and Technology,; Vol. 11(2021)p. 684-694

Artikel i vetenskaplig tidskrift

Development of Supra-THz Schottky Diode Harmonic Mixers

International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz,; (2021)

Paper i proceeding

THz Schottky diode mixers for high resolution FIR spectroscopy

Rymdstyrelsen, 2018-01-01 -- 2019-12-31.

Rymdstyrelsen (170/17), 2018-01-01 -- 2019-12-31.

Styrkeområden

Informations- och kommunikationsteknik

Infrastruktur

Kollberglaboratoriet

Nanotekniklaboratoriet

Ämneskategorier

Elektroteknik och elektronik

Utgivare

Chalmers tekniska högskola

Kollektorn A423

Opponent: Dr. Jeffrey Hesler, CTO, Virginia Diodes Inc. (VDI), USA

Mer information

Senast uppdaterat

2021-11-22