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.

Schottky diodes

Phase locking

Harmonic mixers

Heterodyne receivers

Terahertz electronics

Frequency stabilisation

Frequency converters

Kollektorn A423
Opponent: Dr. Jeffrey Hesler, CTO, Virginia Diodes Inc. (VDI), USA (Passcode for zoom: 587413)

Författare

Divya Jayasankar

RISE Research Institutes of Sweden

Chalmers, Mikroteknologi och nanovetenskap, Terahertz- och millimetervågsteknik

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,; Vol. 2021-August(2021)

Paper i proceeding

THz Schottky diode mixers for high resolution FIR spectroscopy

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

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

THz-metrologi för moderna trådlösa system

Stiftelsen för Strategisk forskning (SSF) (FID17-0040), -- .

Styrkeområden

Informations- och kommunikationsteknik

Infrastruktur

Kollberglaboratoriet

Nanotekniklaboratoriet

Ämneskategorier

Elektroteknik och elektronik

Utgivare

Chalmers

Kollektorn A423

Online

Opponent: Dr. Jeffrey Hesler, CTO, Virginia Diodes Inc. (VDI), USA (Passcode for zoom: 587413)

Mer information

Senast uppdaterat

2022-04-13