Microwave generation using an all polarization-maintaining linear cavity dual-wavelength fiber laser with tunable wavelength spacing

A stable dual-wavelength erbium-doped fiber laser with a linear cavity is formed by a polarization-maintaining uniform fiber Bragg grating (PM-FBG) and a polarization-maintaining linearly chirped fiber Bragg grating (PM-LCFBG), both of which were fabricated on a high-birefringence (Hi-Bi) fiber. Experimental results show stable dual-wavelength lasing operation with a wavelength separation of ∼0.22 nm, which can be tuned down to as small as 0.05 nm and a large optical signal-to-noise ratio (OSNR) of over 40 dB under room-temperature. Microwave signal at frequency of 9.41, 18.03 and 27.46 GHz is achieved by heterodyned the output lasing wavelengths on a photodetector.     

A simple linear cavity dual-wavelength fiber laser using AWG as wavelength selective mechanism

In this paper, a simple design of linear cavity dual-wavelength fiber laser (DWFL) is proposed. Operating in the C-band region stretching from 1538.3 nm to 1548.6 nm, an arrayed waveguide grating (AWG) is used to generate the dual-wavelengths output together with a broadband fiber Bragg grating as a back reflector and an optical circulator with a 10% output coupling ratio which acts as a front mirror. The measured average output power of the DWFL is about −5.66 dBm and with a side mode suppression ratio (SMSR) of 53.1 dB. The spacing between the two output wavelengths can be varied from 0.8 nm to 10.3 nm with a stable output and minimum power fluctuations.     

Actively mode-locked dual-wavelength fiber laser with close wavelength spacing using a fiber Bragg grating

A simple actively mode-locked fiber ring laser is proposed and successfully demonstrated to generate dual-wavelength picosecond pulses with close wavelength spacing using one Bragg grating in standard single-mode fiber. The proposed laser can be made to operate in stable dual-wavelength at room temperature, due to the birefringence characteristic of the FBG induced by transverse strain. Transverse strain loading on the FBG allows the wavelength spacing to be controlled. Generation of stable dual-wavelength pulses with a pulsewidth of 212–234 ps and a tunable wavelength separation from 0.2 to 0.44 nm at a pulse rate of 1.05 GHz was demonstrated.     

Synchronous tunable wavelength spacing dual-wavelength SOA fiber ring laser using Fiber Bragg grating pair in a hybrid tuning package

A Dual-Wavelength Semiconductor Optical Amplifier (DW-SOA) based fiber ring laser with synchronous wavelength tunability is proposed and experimentally demonstrated. The SOA gain medium strongly suppresses mode competition, thus allowing stable dual-wavelength laser oscillation. The wavelength spacing of the two lasers can be tuned synchronously using a modified hybrid-tuning package incorporating a pair of Fiber Bragg Gratings (FBGs). The DW-SOA demonstrates a laser output with a wavelength spacing of between 0.10 and 8.30 nm (wavelength shift inequality of 0.08 to 0.75 nm). The relationship between the applied strain and wavelength shift of the two tuning modes is also analyzed.     

High power dual-wavelength tunable fiber laser in linear and ring cavity configurations

We describe and compare the performances of two crucial configurations for a tunable dual-wavelength fiber laser, namely, the linear and ring configurations. The performances of these two cavities and the tunability in the dual-wavelength output varied from 0.8 to 11.9 nm are characterized. The ring cavity provides a better performance, achieving an average output power of 0.5 dBm, with a power fluctuation of only 1.1 dB and a signal-to-noise ratio (SNR) of 66 dB. Moreover, the ring cavity has minimal or no background amplified spontaneous emission (ASE).     

Double-ring cavity configuration of actively mode-locked multi-wavelength fiber laser with equally tunable wavelength spacing

A novel actively mode-locked multi-wavelength tunable fiber laser with equally increased or decreased wavelength spacing is presented. It is constructed using a double-ring cavity combined with an amplitude modulator and cascaded fiber Bragg gratings (FBGs). The cavity lengths for all FBGs are intrinsically identical due to the double-ring configuration, and simultaneous mode locking of multiple wavelengths is therefore achieved by applying only one mode-locking signal to the modulator. The FBGs are mounted on a organic plate with angles between adjacent gratings such that the forces applied to the FBGs have an equal force increment; thus, stretching or compressing the cascaded FBGs can achieve a wavelength tuning with equally increased or decreased wavelength spacing.This revised version was published online in March 2005. In the previous version, the published online date was missing     

A reconfigurable multiwavelength fiber laser with switchable wavelength channels and tunable wavelength spacing

We report the experimental demonstration of a reconfigurable multiwavelength fiber laser source with switchable wavelength channels and tunable wavelength spacing by spectrum slicing a broadband light source using a tunable comb filter. The tunable comb filter is based on a thermally-induced linearly-chirped fiber Bragg grating (LCFBG). As an example to demonstrate the effectiveness of the method, two wavelength channels with various wavelength spacings and eight wavelength channels with ∼1.6 nm wavelength spacing were experimentally demonstrated. All the wavelength channels have rejection ratios of greater than 20 dB, and very small 3-dB linewidths of ∼10 pm. The multiwavelength optical source has such unique advantages as simple all-fiber structure, switchable wavelength channels, tunable wavelength spacing, very narrow linewidths, and stable room-temperature operation.     

A stable multiwavelength SOA-based fiber ring laser with ultra-narrow wavelength spacing

This investigation demonstrates a stable multiwavelength fiber ring laser with ultra-narrow wavelength spacing using a semiconductor optical amplifier (SOA). A delay interferometer and a mirror are used as a double-pass interferometer to improve the signal-to-noise ratio in this experiment. Up to 181 stable lasing wavelengths with a wavelength spacing of 10.7 GHz and a signal-to-noise ratio of over 24 dB are produced at room temperature.     

Novel discretely tunable narrow linewidth fiber laser with uniform wavelength spacing

A novel configuration of the tunable fiber laser with uniform wavelength spacing in dense wavelength division multiplexing (DWDM) application is proposed. The ring type tunable fiber laser consists of an all-fiber comb filter which determines the wavelength spacing, and a piece of adjustable fiber grating to select the discrete lasing wavelength for WDM application. The proposed all-fiber ring type tunable laser has potential application in the DWDM and other optical systems due to its advantages such as narrow linewidth, easy tuning, uniform wavelength interval, etc..     

Wavelength spacing tunable dual-wavelength single-longitudinal-mode fiber ring laser based on fiber Bragg gratings

A wavelength spacing tunable dual-wavelength single-longitudinal-mode fiber ring laser is presented by employing separated fiber Bragg gratings. By using a saturable-absorption-induced grating filter and a hybrid gain medium formed by a semiconductor optical amplifier and an erbium-doped fiber amplifier, stable single-longitudinal-mode lasing is achieved at room temperature. Wavelength spacing of the proposed fiber laser can be tuned in a range from 0.1 to 1.3 nm.     

High stable single-polarization tunable fiber laser based on Opto-DMD processor and polarization-maintaining fiber devices

A high stable wavelength-tunable fiber laser is experimentally demonstrated by using a digital-micromirror-device (DMD) processor and a polarization-maintaining erbium-doped fiber amplifier (EDFA).The electronic-addressed DMD processor is able to select and couple a waveband from of the polarization-maintaining EDFA back into the fiber ring to generate a narrow line-width laser output. The tunable fiber laser shows a line-width of 0.02 nm, a tuning step of 0.08 nm over the c-band and a side mode suppression ratio (SMSR) greater than 50 dB. The output power uniformity of 0.01 mW is achieved by using the automatic power control (APC) system under room temperature. The center wavelength fluctuation during 1 h is below 0.01 nm.     

L-band erbium-doped fiber laser with polarization-maintaining ring cavity

A new, simple and efficient L-band erbium-doped fiber (EDF) laser with polarization-maintaining ring cavity is proposed and experimentally demonstrated. The laser offers the unique advantage of being a polarization-maintaining lasing, which meets the requirement of external electronic-optical intensity modulation for DWDM communication and interferometric fiber sensors. Theory has been established. Experimental results are given to show that the laser has long-term stability over a couple of hours with 35 dB signal-to-noise ratio at 1598.644 nm and tunable from 1572.167 to 1608.480 nm.     

Simple erbium-doped dual-ring fiber laser configuration for stable and tunable dual-wavelength output

We propose and experimentally investigate a stable and tunable dual-wavelength erbium-doped fiber (EDF) dual-ring laser scheme. Here, two tunable bandpass filters (TBFs) are used inside the dual-ring gain cavity to generate dual-wavelength lasing. And, due to the gain competition of the EDF gain cavity, the mode-spacing (Δλ_s) of lasing dual-wavelength will be limited at different operating wavelengths. Hence, the minimum and maximum mode-spacing in the proposed EDF laser scheme are 0.75 and 15.35 nm in C-band range. Besides, the output performances of proposed fiber laser have also been studied and analyzed.     

Incorporate, switchable dual-wavelength fiber laser with Bragg gratings written in a polarization-maintaining erbium-doped fiber

A stable, incorporate and switchable dual-wavelength fiber laser with two fiber Bragg gratings written in a photosensitive and polarization-maintaining erbium-doped fiber directly, that is, without splices in the laser cavity, is proposed and demonstrated. Simultaneous dual-wavelength oscillation is achieved at room temperature with a wavelength spacing of 0.343 nm. The power fluctuation and wavelength shift of single-wavelength oscillations are measured to be less than 0.24 dB and 0.013 nm over 2 h. The wavelength switchability between single- and dual-wavelength oscillations is realized by altering the voltage upon the electrostrictive ceramic actuator.     

高速宽波长范围可调谐光纤激光器

研制了一台高速波长连续扫描光纤激光器。使用SOA作为增益介质,用高速可调谐法珀滤波器作为波长调谐器件,构成的环形腔激光器。测量结果表明,激光器的平均输出功率2.6mW,波长扫描范围40nm,波长扫描范围内功率波动范围小于±0.4dBm,线宽小于0.01nm,扫描速度达到2kHz。     

Switchable dual-wavelength polarization-maintaining erbium-doped fiber laser using an optical circulator as the all-reflecting mirror

A simple and effective switchable dual-wavelength polarization-maintaining erbium-doped fiber laser is proposed and demonstrated. Only using a uniform fiber Bragg grating written directly in a segment of the photosensitive and polarization-maintaining erbium-doped fiber as the wavelength selector and an optical circulator as the all-reflecting mirror, a stable simultaneous dual-wavelength oscillation is achieved with a wavelength spacing of 0.364 nm experimentally by exploiting the polarization hole burning effect at room temperature. The output can be switched between single- and dual-wavelength by adjusting the polarization controller. The 3-dB bandwidth and the side mode suppression ratio of the laser’s outputs are measured to be less than 0.01 nm and more than 50 dB. The power fluctuation and wavelength drift are measured to be less than 0.50 dB and 0.020 nm over an hour.     

Highly efficient dual-wavelength ytterbium-doped fiber linear cavity laser based on cascaded fiber Bragg gratings

A highly efficient dual-wavelength ytterbium-doped fiber linear cavity laser is experimentally demonstrated. Two cascaded fiber Bragg gratings are used as the wavelength selection component. Stable dualwavelength operation and wavelength-switching modes can be realized by appropriately adjusting the polarization state of the intra-cavity light and the reflectivity of the laser cavity. For dual-wavelength operation, the power difference between the two wavelength lasers (1029.7 and 1040.4 nm) can be less than 0.6 dB and the signal-to-amplified spontaneous emission (ASE) ratio is more than 52 dB. The slope efficiency of the laser is as high as 63.9%.     

A stable and tunable linear polarization single longitudinal mode fiber ring laser

A stable and tunable linear polarization single longitudinal mode fiber ring laser is proposed and demonstrated. A high extinction ratio spatial mode interference filter utilizing two-mode graded-index fiber supresses irregular side modes effectively, the combination of fiber polarizer and polarization maintaining fiber act as a polarization dependent comb filter, and tunable bandpass filter is adopted to select proper lasing wavelength. The power fluctuation and wavelength fluctuation at 1549.88 nm are less than 0.05 dB and 0.02 nm in 1 h, respectively. Only one longitudinal mode appears within a free spectral range of 7.5 GHz, and the degree of polarization in percentage is approximately as high as 99.07%.     

Tunable dual-wavelength fiber laser based on a polarization-maintaining fiber Bragg grating and a Hi-Bi fiber optical loop mirror

We demonstrate experimentally the operation of a linear cavity dual-wavelength fiber laser using a polarization maintaining fiber Bragg grating (PM-FBG) as an end mirror that defines two closely spaced laser emission lines. The PM-FBG is also used to tune the laser wavelengths. The total tuning range is ∼8 nm. The laser operates in a stable dual-wavelength mode for an appropriate adjustment of the cavity losses for the generated wavelengths. The high birefringence (Hi-Bi) fiber optical loop mirror (FOLM) is used as a tunable spectral filter to adjust the losses. The FOLM adjustment was performed by the temperature control of the Hi-Bi fiber.     

Dual-wavelength Brillouin ring-cavity fiber laser with tunable channel spacing

We experimentally demonstrate a dual-wavelength Brillouin fiber laser configured a pre-amplified Brillouin pump and FBG filter in a ring-cavity. The Brillouin laser can generate 21 Brillouin Stokes with 0.084 nm spacing, the first-Stoke has a peak power of 2.19 dBm. By adjusting the TLS wavelength and FBG’s reflection wavelength from circulating in the ring-cavity, the generated output dual-wavelength is stabile and the channel spacing is tunable, the widest and narrowest channel spacing obtained is approximately 1.12 nm (139 GHz) and 0.084 nm (10.5 GHz).