Continuous-wave reflectometer with linear frequency modulated intensity of sounding beam

The construction principles are considered for continuous-wave (CW) reflectometers with linear frequency modulated (LFM) intensity of sounding beam intended for monitoring of fiber-optic communication links. Based on analysis of energy characteristics for square-law photodetection regime of optical signals the capability was substantiated for considerable (about 103....104 times) reduction of sounding beam power for continuous-wave reflectometry regime comparatively to pulsed regime. The analysis of photoresistor operation under radio-heterodyning regime was fulfilled and practical schemes for reflectometry with linear frequency modulated intensity of sounding beam has been elaborated to realize advantages of continuous-wave sounding methods for infrared spectrum band which is especially important for monitoring of fiber-optic communication links. The processes of backscattering signals accumulation were investigated for CW reflectometers with LFM sounding beam and conditions for entire utilization of energy resources for laser emitter were determined. Energy characteristics of CW reflectometers with LFM beam intensity were researched and large range of these systems (86.1 km) was confirmed for sounding beam power 1 mw. These characteristics eliminate from measurement distortions caused by non-linear processes in optical fiber inherent in pulsed systems for the same range. Whole complex of present investigations provides for significant rise of metrological characteristics united with entire utilization of energy resources for laser emitter in reflectometry systems.