# Wave parametric amplifiers

1. Nov 12, 2007

### momentum_waves

I have been working through the book:

John R. Pierce
Dover
2006

This is a fascinating read & offers some deep insights into the inner workings of waves, from a practitioner's perspective.

Chapter 13 - Parametric Amplifiers - is extremely interesting & is something I'd like to research in more depth - particularly for waves in other media.

Many thanks, one & all.

mw...

2. Nov 12, 2007

### marcusl

Parametric amplifiers enjoyed a brief period of excitement in the 50's (mostly) and, except for lasers which are better described in other terms, have disappeared from view. You can go to your university library and find detailed texts most of which will be at least 3 decades old. For optical parametric amplification, see Yariv, Quantum Electronics.

3. Nov 12, 2007

### cesiumfrog

What is a parametric amplifier?

4. Nov 12, 2007

### marcusl

It is a device that amplifies indirectly through some non-linear phenomenon. The term comes from the fact that some parameter (a reactance, for instance) is varied periodically in the circuit. The systems generally have at least three frequencies--a pump frequency, an "idler" frequency and I think the third is the output. A Fluxgate magnetometer is a classic example, where a ferromagnetic core is driven around its hysteresis loop at a "pump" frequency f0, the applied magnetic signal is at DC, and the output is taken at 2f0. The energy flow is described by the so-called Manley-Rowe equations. If anyone is more familiar with this than I, please jump in.

Parametric amplifiers are characterized by unusually low noise. The maser, for example, reigned supreme for decades as a front end amplifier for demanding applications such as radio astronomy. SQUIDS and lasers are also parametric amplifiers. In general, however, describing the devices in parametric terms via the Manley-Rowe equations is complicated, doesn't give much clarity compared to other descriptions (lasers are better described via the Einstein relations plus quantum mechanics, for instance), and so it isn't often done.

Last edited: Nov 12, 2007
5. Nov 13, 2007

### Claude Bile

Optical Parametric Generation (OPG) is an active field of research due to its potential to convert laser frequencies to different parts of the spectrum, which is particularly useful for spectroscopic applications. OPG essentially involves taking an incident photon and splitting it into two photons, whose energies sum to that of the original photon. By manipulating the phase matching conditions in the medium where OPG is taking place, you can "tune" the frequency of the output photons. In addition, the two output photons are entangled, which makes OPG interesting from a Quantum Optics point of view.

Since OPG is a second-order nonlinear optical process, any textbook covering nonlinear optics would most likely contain a section on OPG given that is a somewhat significant application.

Online searches on Optical Parametric Generation/Oscillators/Amplifiers will also yield some good info.

Claude.

6. Nov 13, 2007

### momentum_waves

Thanks so much, marcusl.

I have a particular rather unorthodox application in which I'm working on using the parametric amplifier concept. I was intrigued by Pierce's work.

7. Nov 13, 2007

### momentum_waves

Many thanks Claude.