A novel type of 2×2 polarization independent magneto-optic switch with low Insertion Loss, nanosecond order switching time is designed and analyzed. The study of the magneto-optic switch involves two main parts: Faraday rotator assembly and optical route design. In faraday rotator design, magneto-optic crystal comparison and selection, two types of Faraday rotator assembly schemes design and analysis; high speed magnetic field simulation and generation; nanosecond trigger signal generator design, simulation and experiment are involved. Within optical router design, a simple but effective optical router with 2×2 mode is introduced. The nanosecond trigger signal supply to the Faraday rotator assembly is 12ns. The key characteristics, insertion loss, far-end crosstalk, switching time of magneto-optic switch that developed at a wavelength of 1550nm have been tested and root causes analyzed.
An all-fiber magneto-optic switch is designed in this paper, which makes use of Faraday Effect, fiber-type polarizing beam splitter/combiner (PBS/PBC), magneto-optic crystal fiber, nanosecond impulser and high-speed magnetic field control technology. The design scheme uses magneto-optic crystal fiber instead of bulky magneto-optic crystal. The optical route design includes linear layout of magneto-optic crystal fiber, the optical route design of polarized light in fiber PBS/PBC, magnetic route design and analysis of linear solenoid, etc. A solenoid which is driven by nanosecond current and can generate high-speed magnetic field is designed and manufactured. The result analysis shows that pulse signal can be greatly strengthened by impressed-bias static magnetic field which is perpendicular to transmission direction of light beam. Static magnetic field insures the intensity of induced magnetization where the light passes come back to original value, so that it can offer high-extent magnetization equality. The intensity of magnetic field can be improved to two orders when the length ratio of magneto-optic crystal fiber to solenoid is increased eight times. When the diameter of magneto-optic crystal and solenoid is decreased from three millimeters to one millimeter, the intensity of magnetic field can be improved to one order. The all fiber magneto-optic switch is slim in structure, flexible, easy to high-density integration and expansion, so there are many integration methods to design all-fiber magneto-optic switch array, which is characterized of smaller bulk, higher magnetic field usage, lower consumption and driving voltage, etc.
In the paper, a high speed magneto-optic switch based on the Faraday Effect is designed and analyzed. The optic switch adopts Faraday rotator, nanosecond impulser, and high speed magnetic field, so it is characterized by no moving parts, low transmission loss and polarization insensitive, low optical insertion loss etc. Using the polarization and Faraday Effect of magneto-optic crystal, the magneto-optic switch can hold the function of all-optical switching, which is needed in all-optical communication networks. As the first part of this paper, a design scheme of optical route in high speed magneto-optic switch and its experiment analysis will be discussed. Good avalanche effect of transistor 2N5551 is adopted to generate nanosecond pulse signal and then to drive the high speed magnetic field. Shown by the experiment data, the rising time of the impulse about 10ns, the amplitude of the impulse about 10~60V are available on the Output end from the nanosecond impulser, which can be used as driving current pulse of Faraday rotator. By using the relationship between the polarization plane rotate direction of polarization light and magnetic direction, the Faraday rotator is designed. It's unique double magnetic field and externally applied static magnetic design can greatly speed the excitation time of the internal inductive magnetic field and shorten the switching time of magneto-optic switch.
Magneto-optic switch has been widely researched due to its capabilities handling large beam cross sections, operating at low voltages, featured as low insertion loss and intrinsic non-reciprocity. However, the switching speed is rather slow: switching time of available magneto-optics switches are of hundreds microseconds. Previously, we developed a novel type high speed magneto-optic switch based on Faraday rotation effect of light in yttrium-iron-garnet (YIG). The switch shows its good performance and high reliabilities. However, it had some disadvantages: 1) Although it was polarization independently designed for the insertion loss, some dependence about 0.5dB was observed due to the components' misalignments since it has many components and adjustment points; 2) Faraday rotator assembly designed by using double YIG rods with diameter 3 mm require much higher switching current to rotate the light by 90°. And the heat generated when operating may also affect the YIG performance. 3) The narrow and sharp pulse width of nanosecond trigger impulse signal generated with short duration can't accumulate the high speed switching magnetic field large enough to drive the YIG reach saturation magnetic field within a trigger period. In this paper, we mainly devote to design an improved switch featured as compact optical route, much more effective Faraday rotator assembly and nanosecond trigger impulse signal with wider pulse width.
A novel micro high-speed 2x2 magneto-optic switch and its optical route, which is used in high-speed all-optical communication network, is designed and analyzed in this paper. The study of micro high-speed magneto-optic switch mainly involves the optical route and high-speed control technique design. The optical route design covers optical route design of polarization in optical switch, the performance analysis and material selection of magneto-optic crystal and magnetic path design in Faraday rotator. The research of high-speed control technique involves the study of nanosecond pulse generator, high-speed magnetic field and its control technique etc. High-speed current transients from nanosecond pulse generator are used to switch the magnetization of the magneto-optic crystal, which propagates a 1550nm optical beam. The optical route design schemes and electronic circuits of high-speed control technique are both simulated on computer and test by the experiments respectively. The experiment results state that the nanosecond pulse generator can output the pulse with rising edge time 3~35ns, voltage amplitude 10~90V and pulse width 10~100ns. Under the control of CPU singlechip, the optical beam can be stably switched and the switching time is less than 1μs currently.