An Integrated Fiber-optic White-light interferometry System based on VT-DBR Laser

In this paper, a cost-effective and high-precision optical fiber sensing system based on VT-DBR laser for white light interferometry is proposed. A low-noise, low power, high modulation-bandwidth laser driver with excellent long-term stability is described. A stable and high laser drive current has been obtained using a high-precision ADN8810 chip. Self-designed data acquisition module based on the Analog-to-Digital acquisition chip AD9226 was developed to collect data from Fabry-Perot (FP) sensor interference spectrum, and then the acquired spectral data were transferred to the PC by USB serial port. Laser scanning monitoring, data acquisition and data transmission are carried out using a field-programmable gate array (FPGA). An integral temperature chip ADN8831 was used to drive the thermoelectric cooler controller of the Vernier Tuned Distributed Bragg Reflector (VT-DBR) tunable laser. This system has a broad sweep range (1527-1567nm)with a wavelength interval of 8 pm, and a full-spectrum scanning rate of 100 Hz. Contrast observation of spectrum experiment with commercial optical sensing interrogator sm125 and temperature sensing experiments of FP sensor cavity length demodulation using cross-correlation algorithm was carried out to investigate the performance of the system. Experimental results show that the system is reliable and has superior performance. Benefiting from the self-developed and integrated essential electrical circuits, the whole system has small size, cost-effective and potential application value.