Shiquan Yang

Efficient multi-wavelength fiber laser operating in L-band

In this paper, an efficient L-band multi-wavelength erbium-doped fiber ring laser is demonstrated by recycling backward 1550 nm band amplified spontaneous emission as secondary pump source for the unpumped EDF section. The lasing threshold is reduced and the slope efficiency is improved. A piece of multimode fiber is used as a spatial mode-beating filter. By adjusting the polarization state of the light, the number of lasing wavelength and their spaces are controlled. In dual-wavelength laser, the power of each channel is 4 mW with 40 dB side-mode-suppression-ratio.

Electric current measurement with high resolution using FBG covered by aluminium thin film

We introduce a novel electric current sensor, which is based on a fiber Bragg grating covered by a uniform coat of aluminum thin film which was deposited on the FBG by a simple evaporation method. The Bragg wavelength of the fiber grating shifts when the current flowing through the film varies due to the Joule heat generated by the current. The relationship between the square of the current intensity and the wavelength shift is basically linear. In the experiment, the maximum current can be measured was 43.1 mA with the wavelength sift of about 4 nm and the current sensitivity was about 2.31 X 10-3 nm/(mA)2.

Dual-wavelength actively mode-locked erbium-doped fiber laser using FBGs

We report a dual-wavelength actively mode-locked erbium doped fiber laser constructed using one amplitude modulator as mode locker, two fiber Bragg gratings (FBGs) as wavelength filters and two separate parts of gain mediums in order to minimize gain cross-saturation effects. Dual-wavelength pulses with a wavelength spacing of 0.8nm, 1.6nm, 2.4nm and 3.2nm were simultaneously obtained when the modulation frequency was about 2.5GHz in the experiment, respectively. By adjusting the cavity length of one wavelength with a delay line, the repetition rate of this channel can be changed to as two times as the other channel without changing the modulation frequency.

Wavelength-tunable actively mode-locked fiber ring laser using semiconductor modulator and HiBi fiber loop mirror

Wavelength switching is demonstrated in an actively mode-locked fiber laser by using an F-P laser diode as a modulator and a HiBi fiber loop mirror as a periodic multichannel wavelength filter. By controlling the temperature of the laser diode, wavelength switching in a range ofabout 10nm was achieved.

Electric current measurement using fiber Bragg grating covered by aluminum thin film

We introduce a novel simple current sensor, which is based on a fiber Bragg grating covered by a uniform coat of aluminum thin film. The Bragg wavelength of the fiber grating will shift when the current flowing through the film varies due to the Joule heat generated by the current. The relationship between the square of the current intensity and the wavelength shift is basically linear. In the experiment, we got a current sensitivity of about 2.31x10MIN3nm(mA)2.

Wavelength tunable linear cavity Er-doped fiber laser operating in L-band

A novel method, which utilizes amplified spontaneous emission (ASE) as a secondary pump source, is presented for implanting a linear cavity erbium-doped fiber laser operating in L-Band. The output wavelength tuned from 1583nm to 1600nm, about 17nm tuning range, was obtained in the experiment and the stability of the laser is very good.

Dual-wavelength picosecond pulses generated from self-seeded gain-switched laser diode with fiber gratings

We demonstrate a simple self-seeding scheme for generating dual-wavelength single mode picosecond pulses at a fixed repetition rate with a Fabry-Perot (F-P) laser diode. The F-P laser diode was self-seeded from two fiber gratings that acted as wavelength filters. About 2GHz dual-wavelength pulses with widths of about 45ps and 75ps were achieved when the lengths of external cavities corresponding to different wavelength were equal or different.

Generating different-rate optical pulses in a dual-wavelength actively mode-locked fiber laser using cascaded fiber Bragg gratings

Dual-wavelength operation of an actively mode-locked fiber ring laser generating picosecond pulses was demonstrated by using a cascaded sequence of two fiber Bragg gratings in the laser cavity. By adjusting the distances between the two fiber gratings, simultaneously mode-locked operation of dual-wavelength at different repetition rate could be achieved when the modulation frequency was appropriate. In the experiments, dual-wavelength pulses at about 2GHz latorand 4GHz (when the modulation frequency was about 2GHz) or at about 2.5GHz and 7.5GHz (when the modulation frequency was about 2.5GHz) were simultaneously obtained and each wavelength could be tuned in arrange ofabout 5nm.

Sensitive current sensing base on all-fiber Mach-Zehnder interferometer

A direct current sensor based on all-fiber Mach-Zehnder interferometer is demonstrated in this paper. The phases of interferometric lights in the interferometer is modulated by heat effect when current flowing through a thin metal tube. The charactersistics of current sensing are studied experimentally. Adopting the wavelength scale method, in the case of elimination of environmental perturbation, the wavelength changing range is 32nm when the current changes from 0 to 1.8A. The shifting wavelength is linear to the power and the linear fitting is 0.9987. The tuning efficiency is approximately 19.47nm/W.

Wavelength tuning fiber ring mode-locking laser by tunable chirped fiber Bragg grating

Utilizing large dispersion of a chirped fiber Bragg rating (CFBG), a wavelength tunable mode-locked fiber ring laser was obtained in the band width of the CFBG. Compared with the structure included dispersion compensating fiber, the supermode noise and enviment influence were suppressed. The 2.5GHz pulses were generated.