Laser Diode Control

[LaserSteve]

For the OP, take a look at two papers:

Instrumentation for the Stable Operation of Laser Diodes
 C. C. Bradley, J. Chen and Randall G. Hulet
Review of Scientific Instruments
Rev. Sci. Instrum. 61, 2097 (1990)

It has a simple TC controller that can hold the diode body  to +/- 0.3 Milli Kelvin for periods greater then three hours... Most people can't even measure that small a change... I know my gear can not... At that point, once the current is stable and the temperature is stable, your next enemy for stability is tiny amounts of  back reflection, and that takes a great deal of expertise to deal with, especially with a fiber coupled diode.. Your seeing changes that may be fiber flex noise.

Bryn mawr has that one up for free:

http://www.brynmawr.edu/physics/courses/305/RSI_Bradley.pdf

See also:

A Low Noise High Speed Diode Laser Current Controller
K. G. Libbrech and J. L. Hall
Rev. Sci. Instrum. 64, 2133 (1993)

CALTECH has it on line for free:

http://authors.library.caltech.edu/29621/

Several groups have published low noise, thermally stabilized circuits for spectroscopy on line:

A typical  Google search would be "stabilized diode laser rubidium cesium hyperfine spectroscopy pdf schematic" or some combination of those words..

Or "amplitude stabilized laser diode"  These days you can have a Bragg Grating spliced into the fiber for a bit of wavelength stability, which helps with the amplitude stability...   Or just use Log Ratio detection and cancel out the need for the ultra stable diode..

See the very clever circuit work of P.C.D Hobbs, here:

http://electrooptical.net/www/canceller/noisecan.pdf
http://electrooptical.net/www/canceller/iodine.pdf
http://electrooptical.net/www/canceller/shotnoise_opn.pdf
http://electrooptical.net/www/canceller/snspie.pdf

Then read this one twice...
http://electrooptical.net/www/frontends/frontends.pdf

Book:
http://www.wiley.com/WileyCDA/WileyTitle/productCd-0470402296.html

Hobbs book takes you step by step thru some interesting problems in using lasers for measurement, including back reflection, thermal stability, and interference effects..  I like the part where he tells you that some times you need to crush the window out of photodiode packages, if they are not anti-reflection coated. That step alone saved me on one diode laser  project...




Hobb's book is worth it if you've never designed systems that use electrons and photons at the same time...

When Grouchobyte says this can get difficult, he means it, see this one, then read the reference list... Always read the references and citations on papers...They lead you further down the road, even if your going backwards to get forwards..

http://steck.us/papers/laser.pdf
http://atomoptics-nas.uoregon.edu/unilaser/

The above design is the sort of stuff I deal with on a daily basis in a university lab...

Usually if a Professor posts a link to a paper, you can break down the directory structure on his web page, and if it doesn't 404, you can find more related papers.

I'm told it greatly angers smart people when post a bunch of links and tell people to read them, without explaining the content I link too. SO I'll stop now... I'll make the counter-argument that if you spend a few hours per week re-reading the papers, you can learn it...  Too many people like "instant Gratification Success" from data sheet application notes  and sample circuits these days...   

Steve

[grouchobyte]

@lasersteve

800 ps, nice! Wow that's faster than a pulse generator I did for an electroAcoustic modulator in a Brillioun scattering system (920ps FWHM). I designed that back in 2008.

Also, thanks much for the quality refrence material.

As you most certainly know, this stuff comes in handy and is nice to be aware of before a design is commenced.

BTW Phil Hobbs is brilliant. He has written some stuff on TIAs and photodiode front ends and his insights are remarkably informative. I think he did some time at IBM, if memory serves me right...

Feel free to PM me anytime.

@grouchobyte

[LaserSteve]

Grouchobyte.. Where'[s Home, Toronto per chance?

Steve

[grouchobyte]

Grouchobyte.. Where'[s Home, Toronto per chance?

Steve

Nope

Orignally from Montreal. I PM'ed you.