Tunable and programmable fiber ring laser based on digital-controlled chirped fiber Bragg grating

Gain enhanced L-band optical fiber amplifiers and tunable fiber lasers with erbium-doped fibers

In this paper, we present a continuous-wave tunable fibre ring laser operating in the L-band. A bi-directional pumped L-band erbium-doped fibre amplifier provides gain to the loop. Tunability is achieved by bending a single-mode fibre taper using a micrometer drive, controlling in this way the spectral cavity losses. Laser emission is achieved between 1587 and 1606 nm, and low variation of the output laser power is observed over all the tuning range.

Tunable erbium-doped fiber ring laser based on thermo-optic polymer waveguide Bragg grating

We report on the development of a tunable Raman fiber ring laser especially designed for the investigation of the 3Σ(-)(g) →1 Δg transition of molecular oxygen. Singlet oxygen (1Δg) is a reactive species of importance in the fields of biology, photochemistry, and phototherapy. Tunability of the Raman fiber ring laser is achieved without the use of an intracavity tunable bandpass filter and the laser thus achieves a slope efficiency only obtained up to now in Perot-Fabry cavities. A measurement of the action spectrum of a singlet oxygen trap is made in air-saturated ethanol and acetone to demonstrate the practical application of the tunable Raman fiber ring laser for the investigation of the 3Σ(-)(g) →1 Δg transition of molecular oxygen.

We report on a widely tunable L-band erbium-doped fiber ring laser with the exploitation of an all-fiber Lyot fiber. The all-fiber Lyot filter is constructed from a polarizer, a short section of polarization-maintaining fiber and polarization controllers. Theoretical analysis shows that the laser oscillating wavelength can be tuned by changing the polarization rotation angle. By adjusting the polarization controllers, the laser can be tuned continuously over the full L band (1559.84–1603.19 nm) with a tunability of 43 nm, a side-mode suppression ratio over 44 dB, and power uniformity better than 1.2 dB. The simple and efficient tuning mechanism allows the building of inexpensive widely tunable fiber lasers with all-fiber structure.

A novel narrow linewidth, discretely tunable and stable fiber ring laser based on the matching of the transmission spectra of two fiber Bragg grating Fabry-Perot (FBG-FP) filters is proposed in this paper. We studied the characteristics of this sort of tunable fiber laser both theoretically and experimentally, and obtained eight discretely tunable lasing wavelengths from 1552.24 nm to 1552.912 nm with an average 96 pm spacing, by pulling one of the FBG-FPs. The output of the laser at the discrete wavelengths specified by the transmission maximum of the fixed FBG-FP is quite stable, and the fluctuation of the output power is less than 0.1dB.

In this paper, a tunable single-frequency fiber laser is designed. For narrow linewidth and single frequency operation, a length of 2.75m unpumped EDF as a saturable absorber is used. The FBG co mbined with the unpumped EDF provides narrow frequency selection. Counter propagating beams in the unpumped EDF form a standing wave that results in periodic spatial hole burning. This creates a narrower bandwidth absorption grating than the FBG. The output laser wavelength can be changed from 1530nm to 1570nm by the FBG. The 3dB spectrum width of output laser is 0.08nm and the side mode suppression ratio is 55dB. The maximum output power exceeds 12mW, and the stability is less than ±0.005dB. A nice single-frequency laser is observed. Fr om the relationship of the pump power and output power, it is obvious that the optical bistability switchable phenomena is showed in output characteristics. The bistability switchable phenomena is caused by the saturabl e absorber in the ring cavity. A 10Gb/s codes rate is used in the fiber laser transmission experiment. The high speed optical signal is transmitted in long distance without regeneration. The eye diagrams of optical transmission are measured, the performance of long haul transmission with high speed modulation is perfect. Keywords: optoelectronics and laser; erbium doped fiber; fiber laser; single frequency; bistability

A widely tunable fiber ring laser, utilising a SWNT/polycarbonate film mode-locker and a 3-nm tunable filter, has been realized. 2.3 ps pulse generation over 27 nm spectral range is achieved for a constant pump power of 25 mW.

We propose and demonstrate a novel wavelength tunable single-frequency erbium-doped fiber ring laser. The single-frequency operation is realized by using a coupler loop mirror with an Er/sup 3+/-doped fiber saturable absorber, which acts as a narrow band optical filter. The fiber laser can find applications in microwave photonics systems.

A switchable and tunable ytterbium-doped fiber ring laser (YDFL) is reported and demonstrated. Employing a Sagnac loop mirror fabricated by an 85-cm-long polarization-maintaining fiber (PMF), the proposed YDFL can operate with stable dual-wavelength lasing or tunable single-wavelength lasing around 1 064 nm. Both stable dual-wavelength lasing and tunable single-wavelength lasing are achieved by adjusting a polarization controller in the Sagnac loop mirror. The experimental results show that the output of the proposed fiber laser with two different operation modes is rather stable at room temperature.

We present a broadly tunable active mode-locked fibre ring laser based on a semiconductor optical amplifier (SOA), with forward injection optical pulses. The laser can generate pulse sequence with pulsewidth about 12ps and high output power up to 8.56dBm at 2.5 GHz stably. Incorporated with a wavelength-tunable optical bandpass filter, the pulse laser can operate with a broad wavelength tunable span up to 37nm with almost constant pulsewidth. A detailed experimental analysis is also carried out to investigate the relationship between the power of the internal cavity and the pulsewidth of the output pulse sequence. The experimental configuration of the pulse laser is very simple and easy to setup with no polarization-sensitive components.

A stable and tunable linear-polarization fiber ring laser with a high side-mode-suppression ratio (SMSR) is proposed and experimentally demonstrated by using a compounded fiber filter, which is composed of a dual-pass Mach-Zehnder interferometer filter incorporating one segment of polarization-maintaining fiber and a high finesse filter. By adjusting the polarization controllers, the output laser can be tuned from 1560.37 to 1568.56 nm and an SMSR as high as 72 dB is achieved. In addition, the peak power fluctuation and wavelength shift are monitored to be less than 0.08 dB and 0.02 nm over an hour. Due to the introduction of the compounded fiber filter as a wavelength selector, the side mode of lasing output can be effectively suppressed and mode competition can be weakened. As a result, the SMSR of lasing output is increased and power stability is improved.

Tunable passively Q-switched ytterbium-doped fiber laser using MoWS2/rGO nanocomposite saturable absorber

Thulium fiber lasers emit light of wavelengths spanning as low as 1650nm to 2200nm. This broad emission band is in the “eye-safety” wavelength regime and intersects with the IR atmospheric transmission window with its opacity subsiding past 1900nm wavelength. Consequently, a high power, single frequency, tunable thulium fiber laser with its tuning range from 1900nm to 2000nm has the unique capability of studying high power beam propagation through the atmosphere in regions of both weak and strong transmission. Moreover, such lasers can be made to tune across individual molecular absorption lines due to chemical species present in the atmosphere. This enables a detailed investigation on how individual molecular absorption lines affect the transmission of high power laser beams. In this paper, a 100kHz linewidth, near diffraction limited, 100W class, widely tunable CW thulium fiber laser system is described for atmospheric propagation studies. The fiber laser is of master oscillator power amplifier(MOPA) architecture with one pre-amp and a final power amplifier. The master oscillator is a 5mW class tunable external cavity diode and is tunable from 1900nm to 2000nm. The pre-amp amplifies the seed to 2-3W level, which is then further amplified to 100W by the final amplifier made from thulium doped 25um core 250um cladding 0.09NA fiber from Nufern. All fiber architecture allows efficient lasing at the lossy molecular absorption wavelengths.

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