Stable Multi-wavelength Laser Research Articles

Tunable Brillouin-erbium fiber laser producing multiwavelength cylindrical vector beams

A multiwavelength Brillouin-erbium fiber laser producing cylindrical vector beams with tunable central wavelength and wavelength spacing is presented and experimentally investigated. Owing to the inhomogeneous broadening characteristic of the Brillouin gain, stable multiwavelength lasing is achieved by combination of the cascaded stimulated Brillouin scattering in the ultra-long single mode fiber and the wavelength selection of the fiber Mach-Zehnder interferometer. Multiwavelength lasing with tunable wavelength spacing of about 0.09, 0.11, 0.17, 0.24 and 0.3 nm is achieved by adjusting the optical delay line in the Mach-Zehnder comb filter. With the sufficient pump power, multiwavelength lasing with more than 10 channels is obtained when the wavelength spacing is tuned to be about 0.09 nm. Through adjusting the flat-top tunable bandpass filter, the central lasing wavelength can be tuned from 1534.37 nm to 1570.06 nm continuously. Cylindrical vector beams with purity higher than 93% are produced through regulating polarization controllers on either side of the two-mode long-period grating serving as the mode convertor. Multiwavelength cylindrical vector beams with the largest number of channels and tuning range are obtained to the best of our knowledge.

Design and optimization of unidirectional emitting multi-wavelength InAs/GaAs quantum dot microring lasers on silicon

We proposed a silicon-based monolithic integrated multi-wavelength InAs/GaAs quantum dot microring laser array with radially coupled waveguides. To achieve the stable multi-wavelength lasing of the laser array in the 1.3 μm band, the three-dimensional finite-difference time-domain method is used to numerically optimize structure parameters of the microring laser with a connected III–V waveguide. The results show that the microring laser can realize a stable mode TE50,1 with an outer-wall radius of 3.5 μm, a microring width of 1.0 μm, a cladding thickness of 1.50 μm, an etching depth of 5.255 μm and a waveguide width of 0.5 μm. The mode wavelength is 1302.43 nm with a quality factor of 20,093.6. The optical coupling efficiency from the laser to the waveguide is about 47.8%. Moreover, mode wavelengths can be adjusted by the microring radius. When the microring width is 1.0 μm, changing the outer-wall radius from 2.7 to 3.9 μm with an interval of 0.2 μm, the mode wavelength ranges from 1289.29 to 1307.28 nm with a step of about 3.00 nm. It is feasible to achieve multi-wavelength laser arrays for monolithic silicon integration, which facilitates the preparation of silicon-based III–V multi-wavelength integrated light sources for dense wavelength division multiplexing applications.

Single-pump multiwavelength hybrid raman-EDF laser using a non-adiabatic microfiber interferometer

This paper presents a multiwavelength fiber laser utilizing non-adiabatic tapered EDF based Mach Zehnder Interferometer (MZI) in hybrid Raman-EDF gains design with a linear cavity. A stable laser was obtained from the single pump with a 1497 nm wavelength through the employment of a 20:80 optical circulators and 99% reflective mirror. The generated backward propagating oscillates inside the laser cavity generate the stable multiwavelength output with 4 channels, which is coupled out via the 10:90 coupler and the output laser is characterized using an OSA with a resolution of 0.015 nm. The hybrid Raman-EDF gain is pumped from the external cavity by a Raman Pump Unit (RPU) and produced a stable multiwavelength laser output with SMSR of 28.9 dBm for 300 mW pump power, 30.7 dBm for 1000 mW pump power and 33.7 dBm for 1500 mW pump power.

Multiwavelength erbium-doped fiber laser based on black phosphorus quantum dots packaged by polytetrafluoroethylene

A stable multiwavelength erbium-doped fiber laser has been proposed and experimentally demonstrated based on black phosphorus quantum dots (BPQDs) packaged by polytetrafluoroethylene. The laser mainly consists of a polytetrafluoroethylene packaging device of black phosphorus quantum dots (PTFEPD-BPQDs) and a Lyot filter. PTFEPD-BPQDs have the function of suppressing the mode competition and stabilizing the multiwavelength output. In the experiments, for the unpackaged BPQDs device, BPQDs will degrade and lose its function within 48 h, whereas for the PTFEPD-BPQDs, BPQDs can keep their function for more than 3 weeks. Fifteen stable multiwavelength lasing signals (MWLSs) with the wavelength space of 0.35 nm are achieved. A 10-min optically driven deposition is more conducive to the stable output of MWLSs. The wavelength offset and peak power fluctuation of the output spectrum at central wavelength are 0.1 nm and 0.9 dB, respectively.

Multiwavelength erbium-doped fiber laser based on a polarization-dependent in-line Mach–Zehnder interferometer

A multiwavelength erbium-doped fiber laser based on a polarization-dependent in-line Mach–Zehnder Interferometer (in-line MZI) is proposed and experimental demonstrated. The polarization-dependent in-line MZI demonstrated is constructed by sandwiching a length of polarization maintaining fiber (PMF) between two abrupt fiber tapers fabricated in SMF. The proposed in-line MZI can work as a cost-effective all-fiber-based polarizer. In combination with the nonlinear polarization rotation technique, stable multiwavelength laser comb with uniform wavelength spacing is achieved at room temperature. The wavelength spacing is 0.8 nm. By properly tuning the PCs, the output laser combs with double and triple channel spacing can be also obtained.

Research on Multi-wavelength Fiber Laser Based on Nonlinear Effect

A multi-wavelength erbium-doped fiber laser (MWEDFL) is introduced, which uses highly erbium-doped fiber (EDF) as the gain medium and uses the nonlinear effect of the single mode fiber to suppress the mode competition. In order to obtain higher side mode suppression ratio and flatness, a nonlinear fiber loop mirror is added to the structure. The results show that a stable multi-wavelength laser with 16 lasing wavelengths and a side mode suppression ratio (SMSR) higher than 30dB is obtained.

1.7 μm band narrow-linewidth tunable Raman fiber lasers pumped by spectrum-sliced amplified spontaneous emission.

A 1.7μm band tunable narrow-linewidth Raman fiber laser based on spectrally sliced amplified spontaneous emission (SS-ASE) and multiple filter structures is proposed and experimentally demonstrated. In this scheme, an SS-ASE source is employed as a pump source in order to avoid stimulated Brillouin scattering. The ring configuration includes a 500m long high nonlinear optical fiber and a 10km long dispersion shifted fiber as the gain medium. A segment of un-pumped polarization-maintaining erbium-doped fiber is used to modify the shape of the spectrum. Furthermore, a nonlinear polarization rotation scheme is applied as the wavelength selector to generate lasers. A high-finesse ring filter and a ring filter are used to narrow the linewidth of the laser, respectively. We demonstrate tuning capabilities of a single laser over 28nm between 1652nm and 1680nm by adjusting the polarization controller (PC) and tunable filter. The tunable laser has a 0.023nm effective linewidth with the high-finesse ring filter. The stable multi-wavelength laser operation of up to four wavelengths can be obtained by adjusting the PC carefully when the pump power increases.

Highly Stable, Tapered Fiber Filter-Assisted, Multiwavelength Q-Switched Er-Doped Fiber Laser Based on Tm-Ho Fiber as a Saturable Absorber

A multiwavelength Q-switched erbium-doped fiber ring laser based on a section of Tm-Ho codoped fiber as a saturable absorber, assisted by a tapered optical fiber filter to stabilize the lasing performance is reported. The tapered fiber structure acts as a comb filter that allows us simultaneous lasing wavelengths at 1529.69, 1531.74, and 1533.48 nm with high stability. By adjusting the pump power, optical pulses with repetition rates from 10.46 to 61.8 kHz were obtained. The maximum average output power was 27.61 mW, while 496.34 nJ for the maximum pulse energy. The fiber laser exhibits a power deviation of ± 0.376 dB, an OSNR of 54 dB, and a spectral width of lasing lines of 0.06 nm, with stable multiwavelength lasing.

Multi-wavelength mode-locked erbium-doped fiber laser with photonic crystal fiber in figure-of-eight cavity

A simple passively multi-wavelength mode-locked EDFL is proposed and demonstrated based on figure-of-eight set up. A 50m long PCF and 20km long SMF are incorporated in the cavity as birefringent fiber. The EDFL generates a stable multi-wavelength laser with spacing of 0.47nm and mode-locked pulse at threshold pump power of 137.0mW. By varying the pump power from threshold power to maximum 146mW, pulse repetition rates and pulse width remain as 185kHz and 1.87μs respectively. The maximum pulse energy of 2nJ is obtained at pump power of 146.0mW.

A multi-wavelength fiber laser based on superimposed fiber grating and chirp fiber Bragg grating for wavelength selection

In this paper, a new type of multi-wavelength fiber laser is proposed and demonstrated experimentally. Superimposed fiber grating (SIFG) and chirp fiber Bragg grating (CFBG) are used for wavelength selection. Based on gain equalization technology, by finely adjusting the stress device in the cavity, the gain and loss are equal, so as to suppress the modal competition and achieve multi-wavelength lasing at room temperature. The experimental results show that the laser can output stable multi-wavelength lasers simultaneously. The laser coupling loss is small, the structure is simple, and it is convenient for integration, so it can be widely used in dense wavelength division multiplexing (DWDM) system and optical fiber sensors.

An in-line quasi-Sagnac interferometer based comb filter used for tunable multi-wavelength fiber laser

Abstract An in-line quasi-Sagnac interferometer comb filter based on high birefringence (Hi-Bi) fiber is proposed and experimentally demonstrated. This quasi-Sagnac interferometer is constructed by integrating a high-birefringence (Hi-Bi) fiber in between two fiber-coupled polarization controllers (PCs) followed by a fiber mirror. The filtering function is theoretically analyzed and simulated by the Jones matrix method. The extinction ratio and wavelength interval of the output spectrum can be flexibly adjusted by rotating the PCs. By only using a pump light source and gain medium, stable multi-wavelength lasing operation can be realized at room temperature. These advantages of tunable ability, switchable ability and good stability make the proposed filter to have broad application prospects in the field of tunable multi-wavelength fiber laser.

Dark pulse emission in nonlinear polarization rotation-based multiwavelength mode-locked erbium-doped fiber laser

We experimentally show dark pulse generation in all-normal dispersion multiwavelength erbium-doped fiber laser (EDFL) with a long cavity of figure-of-eight configuration. The EDFL generates a stable multiwavelength laser with 0.47 nm spacing at 24 mW threshold pump power, while the number of lines obtained increases with the pump power. A dark pulse emission is observed as the pump power is increased above 137 mW, with fundamental repetition rate of 29 kHz and pulse width of 2.7 µs. It is observed that the dark pulse train can be shifted to second-, third-, and fourth-order harmonic dark pulses by carefully adjusting the polarization controller. For the fundamental dark pulse, the maximum pulse energy of 32.4 nJ is obtained at pump power of 146.0 mW.

Semiconductor optical amplifier based multi-wavelength lasers in 0.4 nm channel spacing

We propose a multi-wavelength fiber laser employing a double-pass Mach–Zehnder interferometer filter, a piece of polarization maintaining fiber, a semiconductor optical amplifier and an optical isolator. The proposed fiber laser has the advantages of stable multi-wavelength lasing with 33 channels in standard wavelength division multiplexing channel spacing of 0.4 nm using 15 m polarization maintaining fiber. Power ripple among channels could be reduced by increasing the bias current of the semiconductor optical amplifier.

A new mechanism to suppress the homogeneous gain broadening for stable multi-wavelength erbium-doped fiber laser

A suppressant effect of wavelength competition for multi-wavelength lasing oscillations is experimentally demonstrated in an ordinary erbium-doped fiber laser (EDFL). The polarization hole burning is exploited by a segment of erbium-doped fiber (EDF) coiled round the plates of the three-loop polarization controller. The mechanism to suppress the wavelength competition is discussed in detail. Results show that the mechanism is helpful to obtain stable multi-wavelength lasing oscillations at room temperature in the EDFL. By properly adjusting the comb filter, three-wavelength and tunable dual-wavelength lasing oscillations have been achieved. The power fluctuation is measured to be less than 0.75dB over 30min for all the multi-wavelength lasing oscillations obtained in the experiment. The 3dB bandwidth of each lasing oscillation is 0.01nm and the 30dB bandwidth is 0.10nm. The side mode suppression ratio (SMSR) of the three-wavelength lasing oscillation is more than 45dB and that of the dual-wavelength lasing oscillations is more than 50dB.

Tunable multiwavelength erbium-doped fiber laser based on intensity-dependent loss and intra-cavity loss modulation

A tunable multiwavelength erbium-doped fiber laser is proposed and experimentally studied. The intensity-dependent loss (IDL) in a nonlinear optical loop mirror is utilized for stable multiwavelength lasing output. The accurate switch operation, i.e., the lasing lines emerge/disappear one by one at the longer wavelength side of the initial one, is achieved by adjusting the intra-cavity loss using a variable attenuator. The effect of the intra-cavity loss on the lasing characteristics is theoretically analyzed. Numerical results confirm the experiment measurements and suggest that both the IDL and the gain spectrum, which vary with the intra-cavity loss, lead to the observed tunable lasing behavior.

Switchable multi-wavelength fiber ring laser using a side-leakage photonic crystal fiber based filter

A switchable multi-wavelength fiber ring laser is proposed and experimentally demonstrated with a novel side-leakage photonic crystal fiber (SLPCF) based filter incorporated into the ring cavity at room temperature. Stable multi-wavelength laser operations can be achieved due to the spatial mode beating, polarization hole burning and spectral hole burning effects. By adjusting the polarization controller appropriately, the laser can be switched among the single-, dual- and triple-wavelength lasing oscillations whose signal-to-noise ratio is up to 50 dB. In addition, the lasing wavelength can be also tuned and switched by applying the strain to the filter.

Wavelength-spacing tunable multi-wavelength fiber optical parametric oscillator based on multiple four-wave mixing

We propose a wavelength-spacing tunable multi-wavelength fiber optical parametric oscillator (MW-FOPO) with a simple line cavity and one pump source based on multiple four-wave mixing (MFWM). Stable multi-wavelength lasing at room temperature is achieved due to the four-wave mixing effect and the broadband gain of the fiber optical parametric amplifier based on a highly nonlinear fiber. The wavelength spacing of the proposed MW-FOPO can be tuned by adjusting the wavelength of the pump light or the central wavelength of the fiber Bragg grating. Seventeen lasing lines with a wavelength spacing of 2.89 nm and an extinction ratio larger than 10 dB, which covers the wavelength region from 1540 to 1568 nm is demonstrated.

Multiwavelength fiber laser based on a photonic crystal fiber loop mirror with cooperative Rayleigh scattering

In this work, a multiwavelength fiber Raman laser based on a highly birefringent photonic crystal fiber loop mirror is presented. A laser resonator is formed when the Raman amplification with cooperative Rayleigh scattering in a dispersion-compensating fiber is used as a distributed mirror and combined with a photonic crystal fiber loop mirror filtering structure. Stable multiwavelength lasing at room temperature is achieved due to the low temperature sensitivity of the highly birefringent photonic crystal fiber.

Experimental Optimization in Terms of Power Stability and Output Power of Highly Erbium-Doped Fiber Lasers with Single and Hybrid Cavities

In this article, the output power stability of several different highly erbium-doped fiber ring lasers, as a function of the laser parameters, is experimentally investigated. The study is focused on the optimization of several key parameters (erbium-doped fiber length, pump power, and different laser configurations) without changing the basic scheme. The results obtained show that the laser configuration plays an important role in achieving stable multi-wavelength lasing at room temperature in the erbium-doped fiber ring lasers. For an optimized configuration, these power fluctuations are lower than 0.08 dB, showing a notable improvement compared with previously presented work where the output power variations were about 0.2 dB. These lasers have the advantage of a simple all-fiber configuration, low cost, high stability, and operability at room temperature.

FIBER OPTICAL PARAMETRIC OSCILLATOR WITH SWITCHABLE AND WAVELENGTH-SPACING TUNABLE MULTI-WAVELENGTH

We propose a switchable and wavelength spacing tunable multi-wavelength flber optical parametric oscillator (MW-FOPO) with two cascaded flber Bragg gratings (FBGs). The MW-FOPO can operate at two multi-wavelength lasing modes with difierent wavelength spacings, which can be switched by adjusting some polarization controllers (PCs). Stable multi-wavelength lasing at those two difierent operation modes at room temperature is achieved due to the four wave mixing (FWM) efiect and the broadband gain of the flber optical parametric amplifler (FOPA) based on a highly nonlinear flber. The wavelength spacing of the proposed MW-FOPO can be tuned by adjusting the wavelength of the pump light or the central wavelength of the FBG at the two multi-wavelength lasing modes.