Research On Novel Micro-force Sensing Technology Based On Photonic Crystal Resonator

Since the invention of photonic crystals in the eighties of the last century, only within a few decades, photonic crystals have been used a very wide range of applications. From microwave communication devices to terahertz photonic chip, from communications devices, solar cells to bio-Chemical sensed stealth technology. It can be said to have covered a very broad field of optical communications, lasers, and photonic devices. So in recent years the study of photonic crystals is in full swing. One of most important area is the study of photonic crystal micro-cavities. Instead of the traditional cavity, the sensitivity of the sensing systems based on photonic crystal micro-cavity, can be greatly improved. Photonic crystal nano-cavity is easy to be integrated, so that in nano-electromechanical systems, it plays an important role for high sensitivity, miniaturized sensor design and has a very important value in the future.In this thesis, a new methods of photonic crystal micro-cavity are used for micro-force sensing. The main contents include:(1) By comparative analysis, micro-force sensing method based on photonic crystal resonant cavity was selected. It can be found that high quality factor can greatly improve the micro-force resolution. Then the photonic crystals and photonic crystal cavity simulation methods were compared, and FDTD method was chosen. Finally, optimized structure of photonic crystal micro-cavity was obtained for some typical micro-cavity. The quality factor reached more than 5,000.(2) susceptible to various problems that the resonance frequency modulation can be influence by multi-factor for micro cantilever based on force sensor, a new sensing probe is designed, when the system receive micro-power, resonance frequency drift of the micro-cavity is only affected by one factor. This provide high linearity for the sensing. Furthermore FDTD method is used to analyze wavelength drift with the applied micro-force, its detection sensitivity:0.932pm/nN.(3) Finally, the micro-force sensing system wavelength demodulation method based on fiber ring-down technology is proposed. Wavelength drift is change to the light intensity fading time, which eliminated the external noise influences. Then system parameters is selected thorough analysis,3,000-meter-long fiber is selected for delay fiber, as well as two 10:90 couplers. Wavelength demodulation experimental system is set up. Finally, after experiment, resolution of 12pm is obtained for wavelength demodulation.