The paper studies an all fiber high-speed magneto-optic switch which includes an optical route, a nanosecond pulse generator, and a magnetic field module in order to reduce the switching time of the optical switch in the all optical network. A compact nanosecond pulse generator can be designed based on the special character of the avalanche transistor. The output current pulse of the nanosecond pulse generator is less than 5 ns, while the pulse amplitude is more than 100 V and the pulse width is about 10 to 20 ns, which is able to drive a high-speed magnetic field. A solenoid is used as the magnetic field module, and a bismuth-substituted rare-earth iron garnet single crystal is chosen as the Faraday rotator. By changing the direction of current in the solenoid quickly, the magnetization of the magneto-optic material is reversed, and the optical beam can be rapidly switched. The experimental results indicate that the switching time of the device is about 100 to 400 ns, which can partially meet the demand of the rapid development of the all optical network.
With the rapid development of all-optical network, we bring forward more and more requirements to the performance of
the optical switches. Therefore, a novel magneto-optic switch based on nanosecond pulse is designed and investigated in
this study. It is characterized by no moving parts, high switching speed, and small size etc. The research of magnetooptic
switch mainly involves the design of optical route and nanosecond pulse generator. The optical route designment
includes the selection of magneto-optic crystal, the route designment and performance analysis of polarized light in the
MO switches, as well as the design of magnetic route in Faraday rotator. A bismuth-substituted rare-earth iron garnet
single crystal is chosen as magneto-optic material, and a current solenoid is used to generate the applied magnetic field.
The design of nanosecond pulse generator is based on the avalanche multiplier effect of avalanche transistor. Many kinds
of avalanche transistor are studied in the experiment. The experimental results indicate that the rise time of the output
pulse is about 2-5ns, the pulse width is about 6-20ns, while the pulse amplitude is about 30-150V, thereby it is satisfying
for the magneto-optic switch used in all-optic network. By controlling the magnetization of the magneto-optic material,
the optical beam can be stably switched and the measured switching time is about 100-200ns.
In this paper two new types of 1x2 all fiber high-speed magneto-optic switches with thick film ferromagnetic bismuth-substituted
rare-earth iron garnets are proposed and tested. Two types of magneto-optic switches are discussed by using
two kinds of crystals. One is the ordinary switch which needs indurance magnetic field to maintain its state; And the
other is latching type switch, the crystal remains in a given magnetic state for unlimited duration without energy supply.
Circuits used to generate magnetic field are also discussed. The theoretical and experimental analysis of optical route,
measurement of switching time and magnetic filed etc. are included. The extinction ratio of the switches are currently
about 20 dB. It can be improved further by additional Faraday rotation created by another magneto-optic (MO) material
in the light path. The switching time of MO material is under 100 ns, it can be ignored. Magnetic field should be able to
change the voltage rapidly in order to obtain fast operating time of the optical switch. The inductance of the solenoid
used for generating the required magnetic field is the bottleneck for rapid switching of the magnetic field in the MO
material. The switching time of the two optical switch are discussed.
In the paper, a high speed magneto-optic switch based on the Faraday Effect is designed and analyzed. The novel
magneto-optic switch presented in this paper will satisfy high speed transmission and exchange of optical-message
through all-optic network. It consists of three important components as followed novel optical route, Faraday rotator
configuration with ultrafast magnetic field and picosecond impulser. It may switch the optical route by controlling
Faraday rotator which is supplied by picosecond impulser. By the development of the magneto-optic crystal, and
ultrafast magnetic field, the designed magneto-optic switch featured as low insertion loss, low crosstalk, high switching
speed and small bulky size gets ahead of traditional optic switches. 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 FMMT415 is adopted to generate picosecond pulse signal and then to drive the high speed magnetic field.
Shown by the experiment data, the rising time of the impulse about 1ns, the amplitude of the impulse about 100~500V
are available on the Output end from the picosecond 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.
All-fiber magneto-optic switch is presented in this paper which contains both of optical route and high-speed magnetic
field module. The optical route has a 1×2 Fiber Polarization Beam Splitter (FPBS) and a 2×2 Dual Fiber Polarization
Beam Splitter (DFPBS). The high-speed magnetic field module is core of all-fiber magneto-optic switch which changes
the electronic pulse into magnetic pulse to control the light polarization's plane based on Faraday Effect. The high-speed
magnetic field module adopts Yttrium Iron Garnet (YIG) crystal fiber, nanosecond impulser and high-speed magnetic
field, characterized by no moving parts, low transmission loss and polarization insensitive, low optical insertion loss etc.
YIG crystal fiber, the magneto-optic material with high Verdet constant, used to rotate the polarization plane of the
polarized light 90° in all-fiber magneto-optic switch, is grown by Laser Heated Pedestal Growth (LHPG). CMOS chip
FMMT415 which has good avalanche effect is employed to generate the nanosecond pulse. The pulse we measured is
about 10 ns of the rising time and 0~600V of the amplitude and the output current is used to create the magnetic field.
The obtained results indicate that the switch has a potential of low cross-talk, low insertion-loss and high switching speed.
The optical route will be easily and quickly controlled by the means of nanosecond impulser, therefore, and the
switching time is expected to less than 1 μs.
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