A sensitive fiber-optic Fabry-Perot interferometer

A Fabry-Perot interferometric sensor utilizing a single-mode optical fiber has been demonstrated, exhibiting a finesse of 18 and a sensitivity to phase modulation of7.9 times 10^{-7}rad/sqrt{Hz}at 1 kHz.     

Stimulated Raman emission in infrared excited gases

Using the pressure dependence of absorption, absorption coefficients and detunings were measured for CO2pump lines and the strong fat infrared emission in optically pumped D2O. The P (32) CO2line was found to be detuned ∼1.5 GHz from the ν2band transitions6_{6}, 6_{5} rightarrow 5_{5}, 5_{4}. The resulting emission lines at 50.3 μm and 66 μm were found to be detuned from their respective transitions by about the same amount. On the basis of these measurements and gain estimates for the far infrared, the resulting emission lines are identified as stimulated Raman emission.     

Three-photon contributions in optically pumped lasers

A signal flow graph representation of the density matrix equations appropriate to a serial three-wave interaction is introduced, from which perturbation theory and AC Stark shift information may be extracted. The conditions for a large interaction cross section for the three-photon transition are deduced and applied to selected experimental situations with the main conclusion being that the effect may be present in a large number of CW and pulsed experiments.     

Single-mode-fibre point and extended temperature sensors

The response of single-mode fibres to time-varying thermal perturbations has been characterised by using a Mach-Zehnder interferometer. It is shown that single-mode fibres offer the possibility of high-speed, high-sensitivity remote temperature sensing with a minimum disturbance of the thermal environment and the capability to operate in an electro-magnetically active environment. In addition, fibre temperature sensors can be configured to measure not only the specific temperature at any given point, but also offer the unique feature of extended temperature measurements over the length of a fibre segment in which the device optically integrates any thermally induced fluctuations.