Study On The Encapsulation Structure Of Fiber Optic Laser Hydrophone

Fiber optic laser hydrophone is a kind of fiber optic hydrophone which is more promi sing for in-terference type fiber optic hydrophone but develops later.It has the characterist ics of low loss,low cost,small volume,anti-electromagnetic interference,high sensitivity,and corresponding flat freque-ncy.It is mainly used for underwater anti-submarine,oil exp loration,water coast guard monitoring,pipeline water resource leakage control,etc.In add ition to the advantages of laser hydrophone in det-ecting weak signals compared with inter ference hydrophone,laser hydrophone has quickly becom-e research hotspot at home and abroad.Because the bare fiber can not meet the application requirements in the real environment,it is obviously necessary to study the encapsulation structure of hydrophone.Moreover,the package structure is very important for protection of bare fiber,gain of acoustic pressure sensitivity of hydrophone,flatness of frequency response and resistance to acceleration.At the same time,laser hydrophone is divided into vector type and scalar type packaging structure,vector hydrophones also have directivity to consider.The main research work of this paper includes:(1)the research background,current situation and several examples of technology ap plication of hydrophone are discussed.The principle and difference between interfero-met ric fiber optic hydrophone and laser fiber optic hydrophone are analyzed.(2)PGC demodulation,a demodulation scheme of hydrophone,is introduced systema t-ically.Based on the demodulation scheme of the existing hydrophone,several steps were changed by formula derivation,which further improved the accuracy of the demodulation scheme of PGC,and eliminated the influence of the amplitude and modulation depth of the carrier signal.(3)The packaging structure of a vector-type optical fiber laser hydrophone is designed.In addition,a scalar optical fiber laser hydrophone package is designed,and the influence of these parameters on the performance of the hydrophone is a nalyzed from its structure,size and m-aterial coefficient.The principle is derived and the f inite element method is used for simulation verification,which makes it further practical.