Abstract: A gas-sensing apparatus is provided. The gas-sensing apparatus comprises a test chamber formed in a body and comprising a pair of micromirrors. One of the pair of micromirrors is disposed on a first surface of the body and the other of the pair of micromirrors is disposed on a second surface of the body, forming an optical cavity. A light inlet is arranged to couple light into the optical cavity, and light outlets are arranged to receive light from the optical cavity. A gas inlet configured to allow gas from outside of the detector to enter the test chamber. A gas detector comprising a gas-sensing apparatus, a light emitting system, and a light detecting system is also provided.

Abstract: The invention relates to a method for producing a reference frequency ?f. According to the invention, the use of a first optical resonator (3a; 24) and of a second optical resonator (25) is provided, wherein the first resonator (3a; 24) has a first resonator mode having a first frequency f1 and the second resonator (25) has a second resonator mode having a second frequency f2, wherein the frequencies of the two resonator modes are functions of an operating parameter BP and assume the values f1 and f2 at a specified value BP0 of the operating parameter such that f1(BP0)=f1 and f2(BP0)=f2 apply, wherein the resonators (3a; 24, 25) are designed in such a way that the respective first derivatives of the frequencies f1(BP), f2(BP) with respect to BP or at least respective difference quotients around BP0 correspond within a deviation of at most ±0.

Abstract: The invention relates to a method for producing a reference frequency ?f. According to the invention, the use of a first optical resonator (3a; 24) and of a second optical resonator (25) is provided, wherein the first resonator (3a; 24) has a first resonator mode having a first frequency f1 and the second resonator (25) has a second resonator mode having a second frequency f2, wherein the frequencies of the two resonator modes are functions of an operating parameter BP and assume the values f1 and f2at a specified value BP0 of the operating parameter such that f1(BP0)=f1 and f2(BP0)=f2 apply, wherein the resonators (3a; 24, 25) are designed in such a way that the respective first derivatives of the frequencies f1(BP), f2BP) with respect to BP or at least respective difference quotients around BP0 correspond within a deviation of at most ±0.