We report on the development of a new type of hydrophone based on an optical fiber interferometer sensor. This interferometer based on dual Sagnac ring configuration to pick up the underwater acoustic signal. Using the unbalanced arms of the Mach-Zehnder interferometer (MZI), the underwater acoustic wave induces the phase difference on optic fiber hydrophone interrogator to demodulate the acoustic field signals by PGC modulation circuit. The configuration is easily implemented and can detect weak signal in a high noisy water environment. The underwater hydrophone systems primarily with B&K system, projector 8104 and receiver 8103, have been successfully worked. As well, B&K 8104 acoustic response increases with frequency but also causes the echo noise in the meantime. The experimental results show that over the frequency range of 7 to 11 KHz, the hydrophone has an almost flat response with an average sensitivity and dynamic range of -211.47 dB re/μPa and 33dB, respectively.
Optical fiber current sensors have certain privileges that the traditional sensors couldn't support. However, when the fiber is deployed, a large degree of linear birefringence is induced in the fiber. This induced birefringence significantly reduces the sensitivity of the system and quenches the weak Faraday effect signal. We demonstrate that twisted the single mode fiber before it is annealed can largely eliminates the residual linear birefringence. It dramatically improves the possibility to employ the twisted single mode fiber that intrinsically had large residual linear birefringence for constructing an optical twisted electric current sensor. We design a new electric current sensor employing the twisted single mode optical fiber. This sensing system has been verified with good performance. The minimum detectable current was measured to be 1 A and the maximum measurable current up to 2kA with linearity lower than 0.1%, and dynamic range approaches 40 dB. Because of the advantages of high sensitivity, considerable wide dynamic range, and free from electric shock, this novel optic electric current sensor may open a new era in the applications of the electric power system.
We propose a new all-optical switch by using the nonlinear asymmetric Mach-zehnder waveguide structure which is composed of a narrow nonlinear arm and a wide nonlinear arm. The light-induced index charges in the nonlinear asymmetric Mach-Zehnder waveguide structure break the symmetry of the structure and make the output beam swing in the uniform nonlinear medium. We investigate the characterization by using the beam propagation method. By properly launching the input power, the numerical results show that the proposed nonlinear asymmetric Mach-Zehnder waveguide structure could function as an all-optical switch.
We proposed a new all-optical phase-controlled routing switch contain a two-mode tapered waveguide with the nonlinear cladding. This all-optical device is divided into three sections: the input section, the uniform nonlinear medium section, and the output section. In the input section, the two-mode tapered waveguide is in the center between the linear substrate and the nonlinear cladding. The uniform nonlinear medium section is between the input section and the output section. In this nonlinear medium section, the spatial solitons can be excited. In the output section, three nonlinear guides are used to couple out the spatial soliton excited in the uniform nonlinear medium. The swing effect of the spatial soliton is observed in the uniform nonlinear medium section. By properly controlling the relative phase between the TE0 and TE1 waves, the proposed waveguide device could really function as an all-optical switch.
We propose a novel nonlinear all-optical switch by using the phase and power modulation of spatial solitons. The proposed waveguide structure is composed of a straight nonlinear signal waveguide, a nonlinear delay branch, a nonlinear control waveguide, and three nonlinear output guides. By properly launching the control power and varying the length of the delay branch, this nonlinear waveguide structure could really function as an all-optical switch. It could be a potential key component in the application of integrated-optics circuits.
The swing effect of spatial solitons excited by the butt-coupled linear waveguide is investigated numerically. The proposed waveguide structure is composed of a inclined butt-coupled linear waveguide and a straight nonlinear waveguide. In the input section, the inclined butt-coupled linear waveguide is used to launch the input signal beam. In the straight nonlinear waveguide section, the spatial solitons will be excited and swing in the nonlinear waveguide under the perturbation of the linear-nonlinear interfaces. The swing path of the spatial solitons depends upon the input power level as well as the position and the angle between the linear and nonlinear waveguides. The swing effect of spatial solitons excited by the butt-coupled linear waveguide will be useful for designing all-optical switching devices.