Single-ended Brillouin optical time domain analysis system can work in single-ended and measure the sensor information of the broken fiber

which is suitable for large-scale monitoring occasions.The Brillouin Optical Time-Domain Analysis system based on Rayleigh scattering（RBOTDA）realizessingle-ended sensing by impinging pulsed light and pulsed continuous light from the same end of the fiber.The Electro-Optic Modulator（EOM）is used to generate pulsed light and the pulsed substrate is the key technique of RBOTDA system.In order to get pulse light and continuous light in single frequency

two parallel EOM structure is proposed to generate the pulsed light for the RBOTDA system and the optimal operating point of the electrooptical modulator is discussed in this paper.It is proved that the design can produce the first-order double-side baseband continuous light and zero-order pulsed light.The proposed design overcomes the interference with single EOM

and reduces the requirements of EOM.