I am doing an experiment in which using fabry perot filter for laser stabilization.The system is highly dependent on the temperature variations of fabry perot filter.How can I stabilize FP filter for those temperature variations.
Thanks
Alternative Method is to put the Fabry-Perot in an isolated box and heat it above room temperature (~30°Deg) via a closed loop temperature control system.
This setup is simple, rugid and cost-effective.
Dear Naveed,
please regard
"Thermal tuning of optical cavities for parametric instability control "
for further information.
The paper deals with thermal tuning with regards to a mirror. But it highlights the advantageous with regards to a cooling cycle.
With regards to optical-cavities, please consider:
"Tunable Grating Fabry-Perot-Based Wavelength Add/Drop Multiplexer in Silicon Photonics "
Cheers
http://nanophotonics.eecs.berkeley.edu/Publications/Conference/files/4408/Yeh%20and%20Wu%20-%202013%20-%20Tunable%20grating%20Fabry-Perot-based%20wavelength%20addd.pdf
http://www.ligo-wa.caltech.edu/~richard.savage/Papers/techpapers_degallaix.pdf
Alternately you could pass light from another reliably stabilised laser through the filter and feedback (PZT or temp) to stabilise the cavity. You would need to separate the different wavelengths with filters.
It would help if you could tell us what level of stability you need - both in terms of optical frequency and the corresponding temperature changes in the Fabry-Perot. Do you need stability for a few seconds or over several days? Frequency stability of a few Hz, kHz or MHz ?
Bernd's suggestion of an insulated box and heater is worth pursuing. It is easy to implement, low cost, and should give an immediate improvement. If it is not sufficient alone it could still be beneficial in combination with other methods. A box lined with 10 cm thick slabs of expanded polystyrene can work well. If short term stability is paramount, mount the Fabry-Perot cavity on a metal heat sink to increase the thermal mass, and shield the assembly from convection currents.
If you don't have space for a large insulated box, follow Vincent's suggestion of a Peltier on a heatsink, with insulation and shielding from air currents around the cavity.
Are you able to make or procure a Fabry-Perot filter with a lower temperature coefficient? UK National Physical Laboratory use a cavity manufactured from low expansion glass to improve the short-term stability of their optical clocks. NPL also stress the importance of controlling temperature and minimising vibration for best performance - though they may have more stringent requirements than your application: http://www.npl.co.uk/science-technology/time-frequency/research/optical-frequency-standards/optical-local-oscillators
Some commercial offerings and background information here: http://www.stablelasers.com/resources.html
To follow Richard's suggestion you need a stable reference laser. One option is to use a 1542 nm DFB laser locked to the Lamb dip of the P16 transition of acetylene 13C2H2. https://www.osapublishing.org/oe/abstract.cfm?uri=oe-13-23-9196
There are many other transitions that can be used, including other absorption lines in acetylene, but the P16 transition is a recognized secondary wavelength standard. Narrow linewidth DFBs are available in this band with output powers up to 100 mW http://www.em4inc.com/node/25
http://www1.bipm.org/utils/en/pdf/CIPM_list_of_approved_radiations.pdf
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