In Wavelength modulation spectroscopy (WMS) system with a short open optical path to detect the oxygen concentration, the system parameter optimization is the preconditions for the accurate inversion of oxygen concentration. Absorption spectroscopy parameters of oxygen were obtained from the HIRTAN database, and the optimal center wavelength and its wavelength offset were confirmed. The laser's working temperature and direct current were determined according to the absorption peak position of photoelectric detection. Modulation parameters and time constant of lock-in amplifier were determined by analyzing intensity and standard deviation of the second harmonic signal. This method has been applied to detect the oxygen concentration in a glass vial, and the results indicate that the linear correlation coefficient of concentration and the second harmonic intensity is 0.9950. The resolution and stability of the detection system have been improved and it can meet the requirements of industrial field.

Class-D amplifiers offer significant potential for achieving efficient and high-power RF amplification. By converting the collector dissipation of conventional amplifiers into load power components and employing filtering to eliminate unwanted frequencies, Class-D amplifiers achieve superior overall efficiency. This study proposes and investigates a high-efficiency push-pull Class-D power amplifier integrated with a carefully designed matching network. To validate the proposed amplifier’s performance and practical applicability, a proof-of-concept circuit was designed and fabricated. Operating within a frequency range of 7.7 –8.7 MHz, the amplifier achieved notable results, including a power-added efficiency of 89.26% and an output power of 49.54 dBm . The consistency between simulated and measured results underscores the reliability of the proposed design and its potential for practical deployment. This work demonstrates the suitability of the amplifier for wireless Radio Frequency Identification applications, offering a highly efficient solution with enhanced output power and performance. To the best of the authors’ knowledge, this study provides a novel approach to achieving exceptional efficiency and output power, representing a significant advancement in the field of RF power amplifier design.