Emilio Segrè Visual Archives

More than 30,000 photos of scientists and their work

Attention ESVA patrons:

The Emilio Segrè Visual Archives’ site is moving soon and adopting an open access approach to digital image sharing. Once we have transitioned to the new site in 2021, we will no longer charge for our high-resolution digital images or usage fees (note that we do not hold copyright to all the images in our collections and you will still need to obtain permission for those which we do not own).

If you are working on a long-term project, we advise you to wait until 2021 so that you may obtain our copies for free. If you cannot wait until 2021, email us at nbl [at] aip.org and we will do what we can to assist you. We will not be offering refunds for past purchases.

Bell Labs H8

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Bell Labs H8

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We charge a usage fee per photo if the photo is published, reproduced in a product or publicly exhibited. This is not a license in the legal sense. As a non-profit institution, we do not make any money providing these photographs. It is only by assessing usage fees that we are able to cover the cost of providing publication quality copies of our photos, preserving the photograph collection according to archival standards, and providing access to the collection by maintaining an online image database. The copyright holder may charge a fee in addition to our service fee.

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Image title: 
Tellurium crystal diagram
Credit line: 
Bell Laboratories / Alcatel-Lucent USA Inc., courtesy AIP Emilio Segrè Visual Archives, Physics Today Collection

This block diagram shows the input and ouput radiation for a tellurium crystal used at Bell Telephone Laboratories to generate the first parametric amplification of far-infrared light. Three light waves of different frequencies interact within the tellurium crystal to produce optical parametric amplification. Energy from one wave, at the 'pump' frequency, is transferred to two other waves -- the signal wave, which is amplified, and the 'idler' wave, which is generated as a by-product of the parametric amplification. Pulses of about 3-decibel gain in the output signal coincide with the pump pulses, showing parametric amplification occurs. The two input waves are shown here for clarity as separate beams, but in the experiment they enter the tellurium crystal as colinear (or superimposed) waves. The output waves are also actually superimposed; a set of filters separates the signal wave from the idler and the pump frequencies.

Original format: 
1 photographic print (black and white; 10 x 8 inches)
Bell Labs Innovations