Fiber optic pressure sensor for catheter use

A Fabry-Perot pressure chip for use as a pressure sensor when interfaced to an optical fiber, the chip comprising:

• a body comprising a first surface, the body having a first coefficient of thermal expansion (first CTE), and
• a diaphragm covering the first surface and affixed to the body, the diaphragm having an internal and an external surface, the first and internal surfaces being separated by a distance and forming a Fabry-Perot cavity, the diaphragm having a second coefficient of thermal expansion (second CTE) different from the first CTE, the diaphragm further comprising a layer of material on one of said internal surface and said external surface and having a third coefficient of thermal expansion (third CTE) different from the first CTE and from the second CTE, said third CTE being selected such that a thermal expansion of said layer of material causes a mechanical stress on the diaphragm that counters a mechanical stress induced in the diaphragm due to thermal expansion mismatch between the body and the diaphragm, in order to compensate an undesirable deformation of the diaphragm due to temperature and wherein the layer of the material is disposed on one of a central portion and a peripheral portion of the diaphragm.