Tunable light source used in optical fiber sensing
|School||Nanjing Normal University|
|Keywords||optical fiber sensor circuit model SPICE laser diode tunable source|
Laser is the main source used in optical fiber-sensing system. Considering that semiconductor laser has several advantages such as small bulk (cm~3), light weight (g), high reliability, simple configuration and longevity which adapted to environmental changes of oscillation, temperature, humidity etc, laser has been more and more popular in fiber-sensing system. Nowadays, optical fiber-sensing system is developing along two ways, one is WDM and the other is optical fiber-sensing net which make tunable laser to be necessary. By combining broad band source and tunable filter, a tunable laser can be setup. This research can provide practical technology for optical fiber-sensing net.In order to analyze the modulation response performance of the laser diode (LD) and other relevant circuit using PSPICE, the paper describes the model of Fabry-Perot (F-P) laser diode and Vertical-Cavity Surface-Emitting Laser (VCSEL) based on the rate equations, and improves the applicability of the model. By using the macro model method in PSPICE, we can obtain the pulse modulation response and frequency response performance of the laser diode.Then the driven source of PZT is developed. Tunable filter realizes the filtering function by changing the length of cavity, which is made by the micro-displacement of PZT. In this paper, the driven source of PZT is designed and fabricated. The result of the experiment shows that the source has many virtues, such as simple circuit, good linearity, tiny ripple, strong load ability and high frequency response.The central part of this paper is to design and fabricate a tunable source and the main purpose is to design a controller for a tunable filter which is based on the PZT-driven circuit. Tunable laser is fabricated based on both the theory and the practical applications of controller. From the experiment we can see that the response velocity of the light source is quite quick and it can replace tunable laser diode completely in some experiment system.