[The Study on the Influence of Spectral Diffraction Efficiency Based on the Matching Network of Wide Spectrum AOTF]

Given that AOTF (Acousto-Optic Tunable Filter, AOTF) spectral imaging analyzer is widely used in a wide spectral region of the visible and infrared spectrum, the spectral bandwidth, diffraction efficiency and power efficiency of the AOTF need to be improved to meet higher standards. Ultrasonic transducer is the core component of AOTF. Its 3 dB working bandwidth determines the spectral diffraction range of AOTF, so it is making two different thicknesses high-low frequency ultrasonic transducer to improve AOTF spectral bandwidth on the same of the acousto-optic medium. Because between the operating frequency of ultrasonic transducer and input impedance there exists non-linear relationship, they have different input impedances at different frequencies. When the between driving signal source’s output impedance and ultrasound transducer have mismatched, It would produce energy consumption and lead to cannot bring the maximum power transfer to the ultrasonic transducer, so that the spectral diffraction efficiency of AOTF is reduced, and it affected spectral imaging quality. So going through to study theoretical ultrasonic transducer impedance frequency characteristics deeply in this paper designed a new broadband impedance matching network, which has important application reference value of the spectral diffraction efficiency improving. By ADS simulation and actual matching circuit experimental test, experimental results show that impedance matching network’ power efficiency reach to more than 90%, spectral diffraction efficiency get up to 90% in the 60~200 MHz bandwidth, and improve to spectral imaging quality within 420~1 150 nm waveband. The higher diffraction efficiency of the matching network has important implications for the current application AOTF based on spectral imaging technology.