Wide-range frequency sweeping technology for narrow-linewidth laser

Abstract

The invention relates to a wide-range frequency sweeping technology for narrow-linewidth laser. A closed-loop feedback optical phase-locked laser frequency sweeping method is adopted. According to theclosed-loop feedback light phase-locked laser frequency sweeping method, a frequency sweeping light signal emitted by a DFB-LD passes through an unbalanced Mach-Zehnder optical fiber interferometer to obtain an intermediate frequency beat signal; the intermediate frequency beat signal is compared with the low-phase-noise reference signal with the same frequency to obtain an error signal of laserfrequency sweeping nonlinear and phase noise for feedback control of laser driving current. The closed-loop feedback optical phase-locked laser sweep frequency corrects laser sweep frequency and phasenoise through a closed loop to achieve phase locking of beat frequency signals and reference signals, and thus linear sweep frequency optical signals with the phase noise effectively restrained are obtained. According to the wide-range frequency sweeping technology for the narrow-linewidth laser, the closed-loop feedback light phase-locked laser frequency sweeping method is provided, wide-range frequency sweeping of the narrow-linewidth laser is achieved, frequency sweeping nonlinearity is effectively corrected, the laser linewidth is compressed, laser phase noise is reduced, and the measuring distance, the resolution and the sensitivity of equipment are improved.

Description

technical field [0001] The invention relates to the technical field of laser frequency sweeping, in particular to a wide range frequency sweeping technology of a narrow linewidth laser. Background technique [0002] The laser line width and frequency sweep range determine the measurable distance range and positioning accuracy of OFDR respectively. The current laser frequency sweep can be divided into two categories: first, laser internal modulation frequency sweep, which realizes laser frequency sweep by tuning the parameters of the laser resonator. The main technical bottlenecks faced by this frequency scanning method are: the laser line width and the scanning range are mutually restricted, the resonant cavity of the narrow line width laser is long or the composite cavity, and the mode selection mechanism is complicated, which leads to the limitation of the scanning frequency range and the limited positioning accuracy. On the contrary, short-cavity or single-cavity lasers t...

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Problems solved by technology

[0005] The purpose of the present invention is to provide a wide-range frequency sweep technology of narrow-linewidth laser to solve the problem that the laser linewidth of DFB-LD proposed in the above-mentioned background technology can only reach hundreds of KHz-MHz order, poor coherence and optical phase The noise is large, which will lead to a very limited signal-to-noise ratio and measurement distance of OFDR, which can only reach tens of hundreds of meters; second, the relationship between the output frequency of the DFB-LD and the drive current and die temperature is nonlinear, based on The non-linear development of the frequency sweep of the drive current and temperature control will lead to the deterioration of the OFDR distance resolution

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