Update: 2019-08-14 16:30 Source: LUFTMY
The principle of laser microsphere sensor is that total reflection occurs continuously on the surface of microspheres. The microsphere laser sensor excites a unique whispering gallery mode by surrounding the equatorial plane and circling the outer circle.Because of the effect of total reflection, the light wave outside the sphere is evanescent wave, which is a non-propagating wave, so the light outside the microsphere is extremely weak, so it can keep Optical Constraint in a small volume for a long time without any loss of mass.
Microsphere laser sensors have important applications in nonlinear optics, cavity quantum electrodynamics, low threshold laser research and quantum optics. The sensitivity and precision of biosensor, temperature sensor and acceleration sensor are greatly improved due to the effect of microsphere resonator of microsphere laser sensor.
As a result, the wavelength of laser can be changed as a result of the interaction of evanescent wave with peripheral particles. Using conical fiber coupling technology, when a beam of light arrives at the interface from a certain substance, reflection phenomenon will occur. At the same time, microspheres are placed in the appropriate position of the evanescent wave to match the microsphere sensor mode. Then, external light can be coupled into the microsphere from the propagation wave from the outside, and the whispering gallery mode is generated in the laser microsphere sensor.
The laser sensor is detected by changing the relative distance between the microsphere resonator and the coupler. At the same time, the microsphere cavity and waveguide are separated from the bottom layer according to the alternating medium stack composed of high and low refractive index layers.
This sensor affects the intrinsic mode of the resonator by changing the refractive index of the microsphere. The frequency of the laser microsphere sensor changes significantly by conducting heat exchange with the surrounding air and slightly changing the ambient air temperature. The emission spectra at low temperature were used to calibrate the intensity ratio and the temperature of the microsphere, and then the high temperature zone was calculated according to the relationship between the intensity ratio and the temperature.
With the continuous improvement of coupling technology, the precision and sensitivity of laser microsphere sensor will play an important role in the field of sensor technology.