Polarization-maintaining Erbium-doped Fiber Research Articles

Novel Distributed Fiber-Optic Strain Sensor by Localizing Dynamic Grating in Polarization-Maintaining Erbium-Doped Fiber: Proposal and Theoretical Analysis

A novel scheme of distributed fiber-optic strain sensor by localizing a dynamic grating in a polarization-maintaining erbium-doped fiber is proposed. The dynamic grating, which is introduced by launching two counterpropagating coherent light beams into a pumped erbium-doped fiber per gain saturation, is examined. A theoretical model of the dynamic grating is given and used to perform simulations of the reflectivity of the dynamic grating localized by synthesizing the optical coherence function. Theoretical analysis and numerical simulation of the novel sensor scheme show that the Bragg frequency of the dynamic grating will shift according by 0.426 MHz/µε to strain in a typical polarization-maintaining erbium-doped fiber.

Spacing-tunable multiwavelength fiber laser source using a Sagnac loop filter

A novel spacing-tunable multiwavelength erbium-doped fiber laser source based on a Sagnac loop filter is proposed and experimentally demonstrated. The filter, which is coupled together with the laser cavity, consists of a normal 3-dB fiber coupler, a polarization controller (PC1), and a segment of high-birefringence (Hi-Bi) fiber. The active gain medium, which is a polarization-maintaining erbium-doped fiber (PM-EDF) with an elliptical core, leads to possible multifrequency lasing output at room temperature. In the experiment, by changing the setting of the polarization controller (PC2), multiple-frequency lasing lines with different wavelength spacing are obtained. Experimental results show several stable output lasing wavelengths with high extinction ratios at room temperature.

Amplification Characteristics of Polarization-Maintaining Erbium-Doped Optical Fiber.

A polarization-maintaining erbium-doped fiber (PM-EDF) based on the PANDA (Polarization-maintaining AND Absorption-reducing) type fiber technology has been developed as an amplification medium of a polarization-maintaining optical amplifier for 1550 nm band. Detail amplification and polarization characteristics of the PM-EDF have been evaluated for the first time. The carefully designed PM-EDF amplifies the optical signal with a high gain and low noise figure, keeping the state of polarization through the fiber. The amplification performance of the newly developed PM-EDF is the same as that of the conventional erbium doped amplifiers except the polarization characteristics. The achieved characteristics are 35 dB gain for small signal, 4.8 dB noise figure, 70% slope efficiency, 30 dB of polarization extinction ratio even in a fiber coil of 15 mm in diameter. Polarization hole burning is also reported.

Passive mode locking by using nonlinear polarization evolution in a polarization-maintaining erbium-doped fiber

By using a new simple cavity design, in which both linear and nonlinear polarization evolution are reproducibly controlled, we demonstrate passive mode locking in a Fabry–Perot-type erbium fiber laser. The laser generates stable trains of pulses as short as 200 fs with an energy content of 70 pJ at repetition rates as high as 100 MHz.