Research On Wavelength Switchable Multi-wavelength Optic Fiber Laser

As the information of the human society grows rapidly, the communicationcapacity of the optical fiber communication system has further improved. Modernoptical fiber communication system is developing to the Wavelength DivisionMultiplexing and Dense Wavelength Division Multiplexing system that with morechannel numbers and traditional light source that based on the fixed laser wavelengthcannot satisfy the communication system any more. Therefore, multi-wavelengthoptic fiber laser and tunable multi-wavelength optic fiber laser arise at the historicmoment. They simplified the equipment complexity, reduced the equipment costand it is a big improvement of the optic fiber laser development. Wavelengthswitchable multi-wavelength optic fiber laser is developed on the base of the tunablemulti-wavelength optic fiber laser. It can output one or several wavelengths of themulti-wavelength and support the dynamic allocation of the wavelengths in the opticnetwork, which further simplified the equipment complexity and improved thenetwork flexibility.Multi-wavelength switchable optic fiber laser has the all-fiber structure, smallcoupling wastage, small volume, easy to integrate and many other advantages. It is thekey technology of WDM and DWDM in the future, so its property can influence theoptical communication system property directly. Besides, the multi-wavelengthswitchable optic fiber laser is widely used in the spectra measurement and opticalfiber sensing fields. The importance of the multi-wavelength switchable optic fiberlaser is becoming more extrusive and there is an urgent need for its further study toimprove its property.This paper discussed the principle of the realization of optical fiber laser and thetheory of some optical devices in detail firstly. And then, combining the function andcharacteristics of the optical devices, it designed an experimental device that has themulti-wavelength switchable function. Through the experiment, it realized amulti-wavelength switchable optical fiber laser that has an ideal output result andverified the following significant conclusions.1. Erbium-doped optical fiber amplifier is to use the stimulated radiation mechanism of the erbium-doped optical fiber to realize the light signal magnifieddirectly. Using the980nm pump to pump the erbium-doped optical fiber, it get the1550nm laser output; and as the980nm pump power increase, the power of the outputlaser increases. Besides, different pump power, different erbium-doped concentrationand different erbium-doped optical fiber length all affect the amplification gain.2. The number of the multi-wavelength comb of the Sagnac ring filter isassociated with the length of the high refractive polarization maintaining optical fiberin the Sagnac ring filter. The longer the polarization maintaining optical fiber is, themore the multi-wavelength combs got.3. Optical Bragg grating is a all-fiber optical device with the filter function.Most wavelengths could pass through the grating with almost no insertion loss, onlythe wavelength which satisfy the Bragg character will be reflected back, making theoptical Bragg grating has the frequency selective characteristic.4. Insert a Sagnac ring filter that contain two polarization controller into theerbium-doped optical fiber laser and use the optical Bragg grating as the frequencyselective device. By adjusting the angle of the polarization controller, it could tune thecomb characteristic of the Sagnac ring filter and realize the locking function, so as torealize the output combinations of the output multi-wavelengths.