Design considerations and performance analysis of dual photodetector system for reliable laser wavelength and power monitoring

• Published in: Sensors and actuators. A. Physical. Vol. 261; pp. 14 - 23
• Main Authors: Joža, Ana V., Bajić, Jovan S., Manojlović, Lazo M., Milosavljević, Vladimir A., Batinić, Branislav D., Laković, Nikola M., Živanov, Miloš B.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.07.2017; Elsevier BV
• Subjects: 2x2 Coupler; Dual photodetector system; Error analysis; Fiber optics; Lasers; Linearity; Monitoring; Optical fibers; Photodiodes; Photometers; Power monitoring; Ratiometric measurement; Sensors; Spectral sensitivity; Stability; Studies; Temperature dependence; Temperature effects; Wavelength monitoring; Power monitoring; Dual photodetector system; 2x2 Coupler; Wavelength monitoring; Ratiometric measurement
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2017.04.042

[Display omitted] •A simple and low-cost sensor system for reliable laser wavelength and power monitoring is presented.•Three wavelength sensitive components are used: fiber-optic coupler, Ge and InGaAs photodiodes.•Excellent linearity (R2=0.99942) and good repeatability of measurement results were obtained.•Based on the sensor system stability measurement, estimated resolution was 0.017nm.•Recommended applications: optical communications, interrogation of FBG and optical sensors. In this paper, a simple and low-cost sensor system based on dual photodetector for reliable laser wavelength and power monitoring, is presented. Different spectral sensitivities of Ge and InGaAs photodiodes were used to obtain ratiometric measurement of wavelength. As a signal splitter, the 2×2 fiber-optic coupler is used in order to increase further the spectral sensitivity of the system. This system is investigated with tunable laser source in the 1525–1630nm range and has showed to successfully operate in the L-range of wavelengths with high linearity of R2=0.99942. Measurement error around ±0.2nm and repeatability of ±0.16nm are achieved. By measuring system stability, the system resolution of 0.017nm is estimated. Temperature dependence of the system is investigated and measured results proved to be consistent with theory of semiconductor behavior in the function of temperature. The sensor system dependence on changing power of tunable laser source is also investigated. In the range of 4–26mW of the source optical power, the proposed sensor system shows wavelength stability of ±0.1nm.