# Terahertz waves

1. Oct 14, 2003

### jimmy p

After answering a thread in a half aed manner earlier i was wondering if anyone would be able to give me more information on terahertz waves. I know they exist and are suprisingly safe compared to x-rays but i cant remember where they sit in the E.M spectrum. Hopefully i can build up a better knowledge on this new(ish) find, any info would be gratefully recieved

Thanx

2. Oct 14, 2003

Staff Emeritus
Here is a report of a terahertz application that gives the location of terahertz waves as between microwaves (low end) and infra-red (high end). Since infra-red lie just below the visual range and microwaves lie above UHF radio waves, that gives you an idea.

3. Oct 14, 2003

### jimmy p

ok cool that gives me a pretty cool insight to what they are about. If they are between microwaves and Infra-Red does that mean that their wavelength borders between that of the others waves and if so how can they tell which wave is which?

Also could ppl find more industrial usage for terahertz waves or find/write a mini- factsheet about them. I know im askin quite a lot but u guys make more sense than lots of web-pages cos u write more personally!!

Thanx

4. Oct 15, 2003

Staff Emeritus
I found that site by going to www.google.com and entering terahertz wave in the search box. There are plenty of other sites where that came from, and you would benefit by finding them yourself :=)

5. Oct 15, 2003

### jimmy p

I know i know, self learning is better than asking for help but i have some bad experiences from self teaching. I dropped two grades in my Biology A-Level cos i was the only student for A2 so i was stuck in the AS class and told to learn my self...i saw 1 out of 2 of my biology teachers once a week for an hour and despite complaining nothing happened. lol all the information fazes my brain so i ask u guys for help by putting it into english. lol...guess which subject i have to take AGAIN this year...lol

6. Oct 15, 2003

### Njorl

There are also security applications. They can be used, at short ranges, to detect and even image metal items concealed under clothing.

Detection of terrahertz signals could be problematic. There are atmospheric absorption problems in that band. IR is usually detected with semiconductor bandgaps, microwaves are detected with antennae. For terrahertz, you could go either way, but it requires extaordinary measures. You could use lithographically deposited arrays of tiny metal antennae, or engineer a semiconductor material using superlattices or quantum dots to get the right band structure. You would probably need a quantum cascade effect to detect terrahertz in semiconductors.

Njorl