Xiangqiao Mao

Single-polarization, switchable dual-wavelength erbium-doped fiber laser with two polarization-maintaining fiber Bragg gratings

An improved erbium-doped fiber laser configuration for achieving single-polarization, switchable dual-wavelength of orthogonal polarizations oscillations at room temperature is proposed. For the first time, two fiber Bragg gratings (FBGs) directly written in a polarization-maintaining (PM) and photosensitive erbium-doped fiber (PMPEDF) as the wavelength-selective component are used in a linear laser cavity. Due to the polarization hole burning (PHB) enhanced by the polarization-maintaining FBG (PMFBG), the laser can be designed to operate in stable dual-wavelength or wavelength-switching modes with a wavelength spacing of 0.336 nm at room temperature by adjusting a polarization controller (PC). Each lasing line shows a single polarization with a polarization extinction ratio of >25 dB under different pump levels. The optical signal-to-noise ratio (OSNR) is greater than 50 dB. The amplitude variation with 16 times scans in nearly one and half an hour is less than 0.5 dB at both operating wavelength.

An Orthogonal-Polarization Dual-Wavelength Fiber Laser with Stable Output

A new orthogonal-polarization dual-wavelength fiber laser by fabricating a uniform FBG and a chirped FBG in a polarization-maintaining erbium-doped fiber (PM-EDF) is proposed and demonstrated. The wavelength space is 0.18nm and the optical signal-to-noise ratio is greater than 50 dB with pump power of 246-mW. Chirped FBG is used to make the reflectivity wavelengths match between two PM-FBGs much easier. Since both EDF and FBGs are polarization-maintaining without splices and the two wavelengths operate with two orthogonal polarizations, the maximum amplitude variation and wavelength shifts for both lasing wavelength with 3-min intervals over a period of six hours were less than 0.2 dB and 0.005 nm, which shows stable dual-wavelength output.

A compact single-polarization erbium-doped fiber laser by exploiting vernier effect

A compact single-polarization fiber laser with fiber Bragg gratings inscripted in a polarization-maintaining erbium-doped germanosilicate fiber is demonstrated experimentally. The single-wavelength and singlepolarization regime of our studied laser is achieved by applying a radial stress upon one of two gratings and stretching the other one axially to adjust the reflection peak match. Two single-wavelength and singlepolarization lasing lines are realized respectively with fine power stability.

Dual-wavelength erbium-doped fiber ring laser based on one polarization maintaining fiber Bragg grating in a Sagnac loop interferometer

Dual-wavelength with orthogonal polarizations erbium-doped fiber ring laser at room temperature is proposed. One polarization-maintaining fiber Bragg grating (PMFBG) in a Sagnac loop interferometer is used as the wavelength-selective filter. Due to the polarization hole burning (PHB) enhanced by the PMFBG, the laser can operate in stable dual-wavelength operation with wavelength spacing of 0.336 nm at room temperature by adjusting a polarization controller (PC). The optical signal-to-noise ratio (OSNR) is over 52 dB. The amplitude variation in nearly one and half an hour is less than 0.6 dB for both wavelengths.

Switchable dual-wavelength fiber lasers based on a semiconductor optical amplifier and a polarization-maintaining fiber Bragg grating

Switchable dual-wavelength fiber lasers with orthogonal polarizations, based on the semiconductor optical amplifier at room temperature, are proposed. One polarization-maintaining fiber Bragg grating (PMFBG) is used as the wavelength-selective filter in three different laser configurations. Owing to the polarization-dependent loss of the PMFBG, the laser can be designed to operate in stable dual-wavelength or wavelength-switching modes with a wavelength spacing of 0.336 nm at room temperature by adjusting a polarization controller in each laser configuration. The amplitude variation over nearly half an hour is less than 0.1 dB for both wavelengths in each laser configuration, which is more stable than that of erbium-doped fiber lasers with similar configuration.

Higher order mode-based large negative dispersion in step-index fibers for dispersion compensation

The dispersion properties of the index-step higher order mode dispersion-compensating fibers (HOM-DCFs) are simulated using an unequal interval finite difference method in this paper. Large negative dispersion of the first few higher order modes (HOMs) near cutoff are studied comparatively, which is helpful for designing the dispersion compensator based HOM-DCFs.

Novel design of M-profile ytterbium doped fibers for high power fiber lasers

A novel design of M-Profile Ytterbium doped Fibers (YDFs) for high power fiber Lasers was given. The output power was two times higher than that in standard double-cladding fiber under the same threshold of damage.

Temperature dependence of fluorescence in erbium-doped silica fiber

The temperature dependence of fluorescence in erbium-doped silica fiber between ~-30 and ~150°C is discussed. 980nm pumping configuration is used in our experiment. 1450nm and 1531nm wavelengths are chosen to calculate the FIR (fluorescence intensity ratio) at the first time instead of the mostly used wavelengths 525nm and 550nm. It shows that as the temperature increases, the fluorescence intensity increases obviously at short wavelengths but changes a little at long wavelengths. The temperature coefficient can achieve ~0.023dB/°C, and its resolution is improved as the temperature decreases. Because there are many effects in our experiments, so it shows a deviation from the behavior of simulation.

High-concentration erbium-doped fiber-based short cavity ring lasers

A high concentration silica host Erbium Doped Fiber with Bismuth-Gallium-Aluminum co-doped was fabricated. The absorption coefficient of this fiber was up to 19dB/m at the wavelength of 980nm and 42dB/m at 1530nm. Ring structure lasers with different fiber lengths were presented. Their output characteristics were measured and analyzed.

Gain flatness performance of backward-pumped distributed fiber Raman amplifiers with pump wavelengths in different arrangement

The relationship between the gain flatness performances with the pump wavelength spacing in single-stage backward-pumped distributed fiber Raman amplifiers (B-DFRAs) were demonstrated theoretically. It was shown that the gain spectrum of B-DFRA which pump wavelengths were arranged in a geometric proportion interval sequence were flatter than one which pump wavelengths were arranged in an equal interval sequence in the same conditions.