A Comparison between Two Heterodyne Light Sources Using Different Electro-Optic Modulators for Optical Temperature Measurements at Visible Wavelengths

Sensors

Ruey-Ching Twu¹  Yi-Huan Lee² 

[1] Department of Electro-Optical Engineering, Southern Taiwan University, 1, Nan-Tai St., Yung-Kang City, Tainan County 71005, Taiwan;

关键词: heterodyne interferometry;    electro-optic modulator;    optical temperature sensor;   

DOI  :  10.3390/s101109609

来源: mdpi

【 摘 要 】

In this paper we have successfully demonstrated a z-propagating Zn-indiffused lithium niobate electro-optic modulator used for optical heterodyne interferometry. Compared to a commercial buck-type electro-optic modulator, the proposed waveguide-type modulator has a lower driving voltage and smaller phase variation while measuring visible wavelengths of 532 nm and 632.8 nm. We also demonstrate an optical temperature measurement system using a homemade modulator. The results show that the measurement sensitivities are almost the same values of 25 deg/°C for both the homemade and the buck-type modulators for a sensing light with a wavelength of 632.8 nm. Because photorefractive impacts are essential in the buck-type modulator at a wavelength of 532 nm, it is difficult to obtain reliable phase measurements, whereas the stable phase operation of the homemade one allows the measurement sensitivity to be improved up to 30 deg/°C with the best measurement resolution at about 0.07 °C for 532 nm.

【 授权许可】

CC BY   
© 2010 by the authors; licensee MDPI, Basel, Switzerland.