Instant Laser Wavelength Measurement Based on Dual Fabry–Pérot Etalons

An all-fiber-instant laser wavelength measurement scheme based on dual etalons and an optical linear filter is proposed and demonstrated. The linear filter is utilized for the coarse measurement, while the Fabry-Pérot etalons are employed for the fine measurement. By slightly tilting the refractive angle of one etalon, its phase and waveform can be tuned. Thus, the waveforms of two etalons can compensate for each other in measurements, covering the whole range without any dead zone. Various wavelength determination criteria are also discussed for different etalon phase offsets. Finally, a wavelength resolution of 1.38 pm is achieved within the whole C -band (1520-1570 nm). The system exhibits many advantages, such as compact structure, low cost, and fast response.