We have experimentally found that, for a communication system with many PDL and PMD components, the global PDL and the product of the maximum and minimum transmission coefficients (TmaxTmin) are wavelength dependent, even though they were treated as wavelength independent in the most of the simulations. At a given wavelength, however the PDL and PMD elements are concatenated, the global TmaxTmin of the system is equal to the products of the TmaxTmin of each comprising element.
By using the phase modulated optical fiber loop mirror, repetition-rate-doubled or -tripled output is realized in the FM mode-locking fiber laser. 80 and 120GHz transform-limited pulses are experimentally demonstrated.
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.
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.
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.
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.
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.
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.
Without any stabilizing equipment, a multi-wavelength fiber linear cavity laser in L-band was obtained at the room temperature. The cavity was formed by two linear fiber loops. Utilizing the birefringence of the single mode fiber, we can make the reflectivity of these fiber-loops vary periodically with the wavelength. Two polarization controllers (PCs) were inserted into fiber loops. By changing the states of PCs, the number of the lasing wavelengths and wavelength spaces can be controlled.
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.
A new displacement measuring scheme based on simply supported beam is reported and demonstrated. The theoretical formula is derived and the experimental results are given. This device has many characteristics, such as simple structure, high sensitivity and good linearity. It is promising to be used into in-process displacement measurement.
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 1566 nm to 1587 nm, about 21 nm tuning range, was obtained in the experiment and the stability of the laser is very good.
Using the characteristics of precise wavelength-selected and special tuning method of fiber grating, stable pulses train with a wavelength-tunable range of 8 nm at a repetition rate of 2.5 GHZ has been achieved in an actively mode-locked erbium-doped fiber ring laser.
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.
A novel technique for fiber Bragg grating sensor is introduced. The sensor is successfully used to measure wavelength-shift induced to strain and temperature. The experiment results agree with the theory and indicate that the sensor has good linear response capacity and high intensity signal and signal to noise ratio.
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.
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