It is a key procedure of measuring the diode laser wavelength in the wavelength modulation spectroscopy (WMS) technique since it determines the selection of specific modulation amplitude and frequency and thus the overall accuracy of the WMS technique. However, the wavelength modulation frequency of lasers is usually from tens of kHz to hundreds of kHz, which makes the traditional methods difficult to measure the wavelength with the sufficient accuracy and time response rate. Therefore, in this paper, we developed a method to measure the modulated wavelength with improved accuracy and time response rate by using a customized long fiber ring etalon. In the method, the free spectral range (FSR) of the etalon was determined by using two adjacent absorption lines of water. And the amplitude of the laser wavelength and its phase relative to the driving voltage was determined by means of interference peak identification and sinusoidal fitting. Finally, we used the developed method to measure dynamic wavelengths as well as phases of a distribute feedback (DFB) diode laser with the modulation frequency from 1 to 500 kHz and the modulation voltage from 0.2 to 1 V. Based on the measurements, the response characteristics of both the linear and nonlinear wavelengths as well as phases with modulation frequency and amplitude were obtained, which provides necessary data for the application of quantitative and high-repetition WMS technique in combustion diagnostics.

中文翻译：

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以高精度和响应速度测量和分析二极管激光器调制波长

它是波长调制光谱 (WMS) 技术中测量二极管激光波长的关键程序，因为它决定了特定调制幅度和频率的选择，从而决定了 WMS 技术的整体精度。然而，激光器的波长调制频率通常在几十kHz到几百kHz之间，这使得传统方法难以以足够的精度和时间响应率测量波长。因此，在本文中，我们开发了一种通过使用定制的长光纤环形标准具来测量调制波长的方法，该方法具有更高的精度和时间响应率。在该方法中，标准具的自由光谱范围（FSR）是通过使用两条相邻的水吸收线来确定的。并通过干涉峰识别和正弦拟合确定激光波长的幅值及其相对于驱动电压的相位。最后，我们使用开发的方法测量调制频率为 1 至 500 kHz 和调制电压为 0.2 至 1 V 的分布反馈 (DFB) 二极管激光器的动态波长和相位。获得了线性和非线性波长以及具有调制频率和幅度的相位的特性，为定量和高重复WMS技术在燃烧诊断中的应用提供了必要的数据。