Both the fiber and the bulk Fabry-Perot etalons can be made temperature insensitive by the addition of a compensator element. This element adjusts the optical length of the air-gap in the etalon cavity so as to compensate for any changes in the optical length of the fiber or the etalon slab due to ambient...http://www.google.es/patents/US5384877?utm_source=gb-gplus-sharePatente US5384877 - Passive temperature-insensitive fabry-perot etalons
