Gigawatts and beyond solid-state Terahertz generators/oscillators

[Rev. Cheeseman]

TL;DR Summary

Highest power Terahertz oscillator made with a solid-state device instead of vacuum electronics device

According to Vacuum Electronic High Power Terahertz Sources book by John H Booske,

"In solid state electronic devices, the electron stream is a conduction (ohmic, collisional) current whereas in vacuum electronic devices (VEDs) the current is a convection (ballistic, collisionless) current. Thus, the electron transport medium—semiconductor versus vacuum—represents the most fundamental difference between solid state and vacuum electronic devices, respectively. Especially for high power devices needing high power electron currents, the vacuum is a “perfect material” [11]. Electrons moving in a vacuum encounter no scattering. Consequently, VEDs are intrinsically superior at handling high power or high power density [3], [10], [12]. Development of VED sources of THz radiation has, therefore, primarily focused on applications calling for either high average power or high average power density, i.e., relatively high power in a compact package and usually with the highest achievable device efficiencies"

Some people said vacuum tubes will produce the highest power output in generating Terahertz radiation, but I'm wondering if it is possible to make a solid-state Terahertz radiation oscillator or generator that can generate higher power and frequency than any high power vacuum tube Terahertz generator/oscillator. In the absolute sense, I think, both vacuum tubes and solid-state devices are actually very tunable that we can set the power and frequency according to our liking given that we have enough cost and so on. Thoughts?

 

[berkeman]

Welcome to the PF.

Interesting question and interesting field. I do know that for some high-power applications in the more modest frequency bands (like high power radars and radio transmitters), vacuum tube electronics is sometimes preferred. The THz band is new to me though. I found this interesting article with a quick Google search...

https://ieeexplore.ieee.org/document/5993476

 

[Rev. Cheeseman]

Welcome to the PF.

Interesting question and interesting field. I do know that for some high-power applications in the more modest frequency bands (like high power radars and radio transmitters), vacuum tube electronics is sometimes preferred. The THz band is new to me though. I found this interesting article with a quick Google search...

https://ieeexplore.ieee.org/document/5993476

Thank you. That's the full article.

Meanwhile, at the same time, I'm searching for articles that talked about high power (around gigawatt and beyond) solid-state Terahertz generators/oscillators.

 

[Baluncore]

It will come down to your definition, and the costs for any particular wavelength application.

Up to 1 THz the highest power will be generated by a gyrotron, which is a vacuum tube.
https://en.wikipedia.org/wiki/Gyrotron
How far above 1 THz that may hold we do not yet know.

Fundamentally, the temperature of a semiconductor will limit the power available before the “solid-state” semiconductor material is “cooked” and it ceases to operate.

A gas MASER will need a stable chemical with an appropriate transition. Do you preclude that by insisting on a true hard vacuum device?

Do you consider a Ruby LASER to be a “solid-state” device?
https://en.wikipedia.org/wiki/Ruby_laser

 

[Rev. Cheeseman]

First, I have to tell you guys I have a limited understanding in engineering but I just started to be interested in these topics. So, if there is anything wrong please correct me.

I have read some articles on gyrotrons and other vacuum electronic devices like klystrons, backward wave oscillators, vircators, and others. These vacuum electronic devices seem very different from the usual vacuum tubes that we used for audio amplification. Are masers considered to be true vacuum tubes? In my opinion, I see them more like vacuum chambers that work much more differently than true vacuum tubes such as triodes, tetrodes, pentodes, etc. I also tend to look at gyrotrons and others that I have mentioned before to be very different from those true vacuum tubes.

Anyway I just found these articles, 0.5 terawatt laser based on a hybrid architecture for high energy diode-pumped lasers delivering sub-500 fs pulses

And...

The design goal for the “High repetition-rate Advanced Petawatt Laser System” (HAPLS) calls for peak powers greater than one petawatt (1015 watts, or 1,000,000,000,000,000 watts) at a repetition rate of 10 hertz, with each pulse lasting less than 30 femtoseconds, or 0.00000000000003 seconds. HAPLS combines sophisticated semiconductor diode laser technology with advanced optics, integrated control systems and techniques for managing the production of ultra-short pulses of light delivered at a repetition rate that is well-suited for the various applications planned for study at the facility.

Looks like with enough cost and everything, we can make very high power Terahertz (or any radiation) generators/oscillators with both vacuum tubes and solid-state devices. What do you think?

 

[Baluncore]

Looks like with enough cost and everything, we can make very high power Terahertz (or any radiation) generators/oscillators with both vacuum tubes and solid-state devices. What do you think?

I do not think there need be a distinction between vacuum and solid-state devices. The source employed will depend on many things. There is no advantage in a restrictive generalisation.

Terahertz pulses are used for close range surface imaging through fabrics. Increased security explains why it is receiving more attention.

1 Petawatt, for 30 femtoseconds, at 10 Hz rate does sound good.
But the average power would be 1 Pwatt * 30 fsec * 10 Hz = 300 watt.

You should be able to find the following books...
Title: Field Guide to Terahertz Sources, Detectors, and Optics. (SPIE Field Guides FG28)
Publisher: SPIE Press Year 2012, Author(s): Créidhe O'Sullivan, J. Anthony Murphy.

Latest...
Title: Emerging Trends in Terahertz Solid-State Physics and Devices: Sources, Detectors, Advanced Materials, and Light-matter Interactions.
Editors: Arindam Biswas, Amit Banerjee, Aritra Acharyya, Hiroshi Inokawa, Jintendra Nath Roy
Publisher: Springer, Year: 2020, ISBN: 9811532346, 9789811532344

20 years older...
Title: Terahertz Sources and Systems. Edited by R. E. Miles, P. Harrison and D. Lippens.
Publisher: Springer, Year: 2001, ISBN 978-0-7923-7097-0

 

[f95toli]

You need to define what you mean by "THz".
BWOs and other conventional electronics work well up to a few hundred GHz.
A the other end you have various FIR lasers etc which tend to work down to perhaps 2-3 THz,

The "problem" is the range from maybe 750 GHz to say 2 THz. This is -AFAIK- the range where there is a need to develop new sources and detectors.

You also need consider what "high power" mean for radiation that can be relatively easily focused. In many applications "high power" would mean say 1-2 watts; I don't know of any THz applications that require hundreds of Watts.

 

[Rev. Cheeseman]

You need to define what you mean by "THz".
BWOs and other conventional electronics work well up to a few hundred GHz.
A the other end you have various FIR lasers etc which tend to work down to perhaps 2-3 THz,

The "problem" is the range from maybe 750 GHz to say 2 THz. This is -AFAIK- the range where there is a need to develop new sources and detectors.

You also need consider what "high power" mean for radiation that can be relatively easily focused. In many applications "high power" would mean say 1-2 watts; I don't know of any THz applications that require hundreds of Watts.

I should rephrase it as from 1 Terahertz, which is already in the infrared region, and beyond.

According to some articles I've found online, not sure if I understand them correctly, the maximum frequencies that gyrotrons can generate are around 1 THz to 1.7 THz with highest power output around several gigawatt.

This article https://www.osti.gov/biblio/6233581...-simulation-technology-laboratory-guide-users talked about a gamma ray generator (more like a particle accelerator) with 15 terawatt power output and very high energy at 20 megavolt. It have electrodes such as a cathode and an anode in a vacuum chamber like a typical vacuum tube, but is it a true vacuum tube or not I'm not sure.