Showing papers on "Polarization-maintaining optical fiber published in 2023"

Plasmonic metafiber for all-fiber Q-switched cylindrical vector lasers

Abstract: Abstract Metafibers, by integrating metasurface at the optical fiber tip, are emerging as the significant optical coupling platforms for nanophotonics and fiber-optic communities. Here, we propose a plasmonic metafiber for converting the fundamental mode to first-order mode in fiber, and as proof of device performance, demonstrate an all-fiber Q-switched cylindrical vector laser using the metafiber. Based on polarization-dependent plasmonic resonance, a polarization-independent mode conversion metasurface is designed theoretically and numerically, fabricated directly on fiber facet, and packaged as an all-fiber component with efficiency up to 21% at 1550-nm band. Using the metafiber in an all-fiber laser, Q-switched azimuthally polarized beam (APB) and radially polarized beam (RPB) are delivered at wavelength of 1548.5 nm with pulse durations from ∼7 to ∼2 μs when pump power increases from 30 to 120 mW. The mode purities of the APB and RPB are 86.5% and 90.7%, respectively. This work outlines a new strategy to integrate metasurfaces into “all-in-fiber” systems and offers a reliable route to construct next-generation laser sources, such as all-fiber ultrafast structured lasers.

All-Solid Single-Polarization Anti-Resonant Fiber Base on Anisotropic Glass

Abstract: A single-polarization solid-core anti-resonant fiber is proposed, and the influence of the fiber core material anisotropy of the solid-core anti-resonant fiber on polarization characteristics is investigated using the finite element method. Single-polarization guidance is achieved by using the anisotropy of optical fiber materials, which also ensures high birefringence. The numerical simulation results indicate that there are two single-polarization intervals (1210–1440 nm and 1490–1560 nm), with a maximum bandwidth of up to 230 nm, when the confinement loss difference between the two orthogonal polarizations exceeds two orders of magnitude. Specifically, when the work wavelength is 1550 nm, a polarization extinction ratio (PER) of 108 is obtained by optimizing the structure parameters. Additionally, the y-polarization fundamental mode (YPFM) can be well confined in the fiber center with a low confinement loss of 0.04 dB/m, while the x-polarization fundamental mode (XPFM) has a huge confinement loss larger than 4.65 dB/m due to the coupling with the tube mode. The proposed single-polarization solid-core anti-resonant fiber has a huge potential in applications such as laser systems, fiber-optic gyroscopes, and optical fiber communications.

Polarization dynamics, stability and tunability of a dual-comb polarization-multiplexing ring-cavity fiber laser

Abstract: In this paper, we present a polarization-multiplexed system capable of generating two stable optical frequency combs with tunable frequency differences in the range from 100 to 250 Hz and an extinction ratio of 16.5 dBm. Also, the polarization dynamics of a dual-frequency comb generated from a single mode-locked Er-doped fiber laser are experimentally studied. The obtained results will extend the application to areas such as polarization spectroscopy and dual-comb-based polarimetry.

Highly birefringent one-air-hole panda fiber.

Abstract: This Letter proposes a highly birefringent one-air-hole panda fiber, which is fabricated by corroding a single stress zone of the traditional panda-type polarization-maintaining fiber (PMF). An additional geometric asymmetry is induced in the fiber to increase the birefringence effect and enhance the light-matter interaction, which improves the performance of the sensor and the device applications of the special fiber. A theoretical and experimental analysis of the one-air-hole panda fiber demonstrates that the birefringence of the fiber can be of the order of 10-3, which is one order of magnitude higher than that of the traditional panda-type fiber. The corroded region provides a microchannel to be filled with a functional material to compose optical fiber sensors; a sample of a salt solution was filled into the microchannel to measure the refractive index with a sensitivity of 3760 nm/RIU (refractive index units).

High Power Ytterbium-Doped Fiber Lasers Employing Longitudinal Vary Core Diameter Active Fibers

Abstract: Thanks to the advantage of balancing nonlinear effects and transverse mode instability, vary core diameter active fiber (VCAF) has been widely used in high power ytterbium-doped fiber lasers in recent years. Up to now, VCAF has developed from the basic form of the original tapered fiber to the spindle-shaped and saddle-shaped fiber with different characteristics and has been applied in conventional fiber lasers, oscillating–amplifying integrated fiber lasers, and quasi-continuous wave fiber lasers and successfully improved the performance of these lasers. In the present study, a 6110 W fiber laser amplifier is realized based on a tapered fiber. The maximum output power of a fiber laser amplifier based on spindle-shaped fibers is 6020 W with a beam quality of M2~1.86. In this paper, we first introduce the basic concept of VCAF and summarize its main fabrication methods and advantages in high-power fiber laser applications. Then, we will present the recent research results of high-power fiber laser employing VCAF in our group and clarify the outstanding advantages of VCAF compared with the constant core diameter active fiber (CCAF).

Three-dimensional micro displacement sensor based on fiber SPR mechanisms.

Abstract: Three fiber micro displacement sensors can be combined to realize three-dimensional (3D) displacement sensing, but the system is complex. In this paper, a 3D displacement sensor based on fiber SPR was proposed, which was composed of displacement fiber and sensing fiber. By cascading the eccentric dual-core fiber and graded multimode fiber, the displacement fiber was realized. The V-groove was processed in the vertical and horizontal directions of the graded multimode fiber, and the inclined SPR sensing areas were fabricated to realize the sensing fiber. A straight beam from the middle core of the displacement fiber contacted the vertical V-groove inclined plane of the sensing fiber to realize the Y axis (up and down) direction micro displacement, contacted the horizontal V-groove inclined plane of the sensing fiber to realize the Z axis (front and back) direction micro displacement sensing. An oblique beam from the eccentric core of the displacement fiber cooperated with the sensing fiber to realize the micro displacement sensing in the X-axis (left and right) direction. The testing results indicate that the fiber SPR 3D micro displacement sensor can sense micro displacement in the X axis, Y axis and Z axis, and the wavelength sensitivity is 0.148 nm/µm, -3.724 nm/µm and 3.543 nm/µm, respectively. The light intensity sensitivity is -0.0014a.u./µm, -0.0458a.u./µm and -0.0494a.u./µm, respectively. When adjusting the parameters of eccentric dual-core fiber, the larger the core distance is, the greater the displacement sensitivity in the X-axis direction of the sensor is, and the smaller the detection range is. The proposed sensor can realize 3D micro displacement sensing by itself, which is expected to be used in the field of 3D micro displacement measurement and 3D space precision positioning.

Fiber Laser Sensor Configurations for Refractive Index, Temperature and Strain: A Review

Abstract: Fiber laser sensors have been present for almost four decades as versatile sensing devices with a simple demodulation process, high sensitivity, and competitive resolution. This work discusses the most representative fiber laser sensor configurations employed for detecting critical parameters such as temperature, refractive index, and strain. However, essential information about other interesting parameters that have been measured is considered in this manuscript. Concurrently, the sensing elements and principle operation are described. Furthermore, these configurations are analyzed in terms of their principle of operation, sensitivity, gain medium, and wavelength operation range. According to the literature reviewed, fiber laser sensors offer the possibility of new interrogation techniques and simultaneous, independent detection. Considering interferometric fiber sensors, the fiber laser sensors offer high brightness, good output power, and high resolution. As a result, it is demonstrated that fiber laser sensors are a robust alternative for multiple sensing applications.

All Optical Fiber Sensor Based on Asymmetric Staggered Taper and Optical Fiber Bitaper Structure

Abstract: A composite interferometric all-fiber sensor based on an asymmetric misaligned tapered multimode (ASTM) fiber configuration has been designed and investigated. This optical fiber sensor combines the asymmetric staggered taper (AST) structure, single-mode multimode single-mode (SMS) optical fiber and optical fiber bitaper (OFB) structure during preparation. The ASTM-OFB allows for efficient measuring of strains and temperature changes compared to conventional SMS fiber optic architecture. The experimental measurement results show that this new ASTM-OFB fiber optic sensor has two obvious resonance peaks near 1500 nm and 1580 nm, and its strain sensitivity is -37.85 pm/με and -71.92 pm/με respectively, which is about 42 times higher than that of the conventional SMS sensor; the temperature sensitivities in the two resonance peaks are 25.23 pm/°C and 26.47 pm/°C separately. The ASTM-OFB fiber optic sensors measure strain and temperature changes simultaneously with a temperature-strain crosstalk sensitivity of only 0.36 με/°C; its ASTM and OFB structures are prepared by common optical fiber fusion splicing mechanism, with a simple structure, controllable processing parameters and cost-effective.

In-fiber Mach–Zehnder interferometer based on polarization-maintaining fiber for displacement and temperature sensing

Abstract: A displacement sensor based on polarization-maintaining fiber has been proposed and proved in experiment. The polarization-maintaining fiber (PMF) is sandwiched with two graded-index multimode fibers (GI MMF), which form the Mach–Zehnder interferometer (MZI) sensor. Graded-index multimode fiber serve as an optical coupler for modes conversion. The results show that with the increase of displacement, the spectrum moves to the long wavelength direction, but when temperature increases, the spectrum has a red shift, which means that the displacement and temperature can be measured separately according to the wavelength drift direction. The sensor consists of 4 mm GI MMF and 14 mm PMF, which can exhibit the displacement sensitivity of –9.275 pm/μm in the range of 0–600 μm. In addition, temperature will also affect the sensitivity of displacement measurement, so the sensitivity of the sensor to temperature is also measured. The results show that the selected monitoring dip provides a better temperature sensitivity of 33.605 pm/℃ in the range of 35–75℃. The sensor is easy to fabricate and does not has any functional coating, which make it become a good candidate in the industrial field.

Quantitative study of birefringence effects in fiber-based orthogonal-pump FWM systems.

Abstract: Optical fibers have unwanted residual birefringence due to imperfections in fabrication processes and environmental conditions. This birefringence will randomize the state of polarization of propagating signals and may harm the performance of four-wave mixing based processing devices. Here, we present a quantitative study of the effects of birefringence in orthogonal-pump four-wave mixing systems, and identify different regions of operation of the optical fiber, mainly determined by the relative magnitude between the physical length L and beat length Lb. This finding clarifies the characteristics of the complex interplay between birefringence and four-wave mixing and advises appropriate fiber length selection for minimized polarization dependent gain.

Multi-band polarization switch based on magnetic fluid filled dual-core photonic crystal fiber

Abstract: The research of high-performance polarization controllers is of great significance for expanding the application field of polarization optics. Here, a polarization switch is demonstrated by using a dual-core photonic crystal fiber (DCPCF) with four symmetrical air holes, placed above and below each core, filled with magnetic fluid (MF). The switch, which utilizes a magnetic field to change the coupling length ratio of the x and y polarization modes, enables dynamic tuning of the polarization state and extinction ratio. Numerical results show that when the working length is 36.638 mm, the magneto–optical polarization switch can operate in four communication bands, i.e., 1509 nm to 1520 nm, 1544 nm to 1556 nm, 1578 nm to 1591 nm, and 1611 nm to 1624 nm. Moreover, the extinction ratio (ER) is greater than 20 dB in the fiber length range of 38.5 mm to 38.7 mm, indicating that the device has a good fault tolerance for the interception of the fiber length.

High birefringence single-polarization composite structured anti-resonant fiber

Abstract: We propose a highly birefringent, single-polarization composite structured anti-resonant fiber (CS-ARF). The proposed CS-ARF has an elliptical core, two symmetrically spaced arrays of elliptical air holes, and a six-tube anti-resonant structure. The birefringence and single-polarization characteristics of the proposed CS-ARF were analyzed in detail in the mid-infrared band using the finite element analysis method. The results show that the fiber can achieve birefringence up to the order of 10−2 and single-polarization transmission with a confinement loss (CL) below 10−5 dB/m in the mid-infrared band. When the refractive index of the elliptical core is set at na = 2.70, the designed CS-ARF maintains single polarization in the range of 2.5 μm to 3.197 μm with an extinction ratio of up to 1.08 × 107. In addition, we found that by setting the refractive index of the elliptical core, the CL in the y-polarization direction can be effectively adjusted.

Measurement of the birefringence variation induced by dihydrogen diffusion into a polarization-maintaining fiber.

Abstract: We report continuous measurements of the transmission spectrum of a fiber loop mirror interferometer composed of a Panda-type polarization-maintaining (PM) optical fiber during the diffusion of dihydrogen (H2) gas into the fiber. Birefringence variation is measured through the wavelength shift of the interferometer spectrum when the PM fiber is inserted into a gas chamber with H2 concentration from 1.5 to 3.5 vol.% at 75 bar and 70°C. The measurements correlated with simulation results of H2 diffusion into the fiber lead to a birefringence variation of -4.25 × 10-8 per mol m-3 of H2 concentration in the fiber, with a birefringence variation as low as -9.9×10-8 induced by 0.031 μmol m-1 of H2 dissolved in the single-mode silica fiber (for 1.5 vol.%). These results highlight a modification of the strain distribution in the PM fiber, induced by H2 diffusion, leading to a variation of the birefringence that could deteriorate the performances of fiber devices or improve H2 gas sensors.

Self-imaging-based high-power all-fiber coherent combiners: fabrication and preliminary demonstration.

Abstract: Self-imaging combiners can achieve near-perfect filled-aperture coherent beam combination in an all-fiber format with a high-power operation capability. In this Letter, the fabrication of proposed self-imaging combiners is presented, along with a demonstration of a 2 × 2 configuration that uses commercially available large-mode-area fibers, glass tube and square-core fiber. Two types of self-imaging combiners have been fabricated using polarization-maintaining fibers and non-polarization-maintaining fibers, respectively, and these have been tested in an all-fiber coherent beam combination system. Preliminary results reveal that non-polarization-maintaining fibers can achieve better positioning precision, and a maximal combining efficiency of 52.7% has been achieved. The deviation of the demonstrated combining efficiency from the theoretical prediction is mainly attributed to the distortion of the fiber bundle and square-core output fiber, which can be further improved by refining the fabrication process and employing specially developed square-core fiber with better geometrical precision. To the best of the authors' knowledge, this is the first validation of all-fiber coherent beam combining based on the self-imaging effect.

Optimization of the optical coupling efficiency of fiber with Gaussian pulsed laser

Abstract: In the photoacoustic microscopy coupled with the optical fiber, the photoacoustic intensity of the irradiated tissue is one of most important factors of Furthermore, the coupling coefficient of the fiber also impacts the final irradiated laser energy. Furthermore, the coupling coefficient of the fiber also impacts the final irradiated laser energy. At the characteristic wavelength of 532nm, the effects of the optical positions of the With the operations of parameters scanning, the optimal values of the optical positions of the focusing lens and optical fiber on the coupling efficiency of the fiber were investigated. values of the optical positions of the focusing lens and optical fiber were obtained under the maximum coupling efficiency of the fiber. After that, the effect of the fiber's mode field diameter on the coupling efficiency of fiber under the optimal positions of the focusing lens and fiber was also investigated. The coupling efficiencies of fiber corresponding to seven different mode field diameters of fiber from 1 to 9μm were computed, the The study results show that with the increase of the mode field Under the optimal positions of the focusing lens and the fiber, as well as the mode field diameter, the optical efficiency of fiber first increase then decrease. Under the optimal positions of the focusing lens and the fiber, as well as the mode field diameter, the optical efficiency of fiber can be improved from 23.174% to 91.638%. Therefore, the reasonable positions of the optical path and the mode field diameter of the fiber are all important to ensure the satisfactory optical Therefore, the reasonable positions of the optical path and the mode field diameter of the fiber are all important to ensure the satisfactory optical coupling efficiency in the photoacoustic microscopy system coupled with the optical fiber.

Digital calibration method enables depth-resolved all-fiber polarization sensitive optical coherence tomography with an arbitrary input polarization state

Abstract: We report a fully integrated all fiber-based polarization sensitive optical coherence tomography (PSOCT) system, allowing depth-resolved and polarization mode dispersion free PSOCT images with single arbitrary input polarization state.

Research on fusion splicing polarization-maintaining anti-resonant hollow-core optical fiber and conventional polarization-maintaining fiber

Abstract: In this paper, in view of mode field matching problem between the anti-resonant hollow-core optical fiber and the conventional optical fibers. We introduce an intermediate SMF fiber with thermal expanded core (TEC) at one end as a transition fiber; at the same time, when we fusion splicing, we use multiple heating methods to avoid the transitional collapse of optical fibers. The optical fiber rotation method is used to monitor the change of optical power and achieve high matching to the shaft to obtain a higher extinction ratio.

Yb-Doped Mode-Locked Fiber Laser Based on an All-Fiber Interferometer Filter

Abstract: An interference filter is designed by fusing a segment of multi-core fiber (MCF) between two segments of multimode fibers (MMFs), which is then spliced between two segments of single mode fibers (SMFs). The light is split into the cladding and different cores of the MCF through the first segment of MMF, which is then coupled back into the core of SMF by the second segment of MMF. When the lengths of MCF are selected to be 4 mm and 10 mm, the 3 dB bandwidths of the filters around 1060 nm are 8.40 nm and 4.84 nm, respectively. Applying these filters in an Yb-doped fiber laser mode-locked by nonlinear polarization rotation, stable pulses have been obtained. Compared with the reported interference filters, the filter proposed in this paper has the advantages of simple fabrication process, compact structure and high environmental stability.

Mode conversion between fibers with different refraction index distribution based on adiabatically tapered structures.

Abstract: Different fibers generally have different mode characteristics so their connections in many practical applications often require mode conversion. The feasibility of mode conversion between fibers with different refractive index distributions based on adiabatically tapered structures is theoretically analyzed. The first kind of mode conversion is between ring core fiber and convex core fiber; the second kind is between multicore fiber and single-core fiber. Three common tapered structures are investigated: tapered core, diffused core, and tapered cladding. The analysis results show that mode conversion by a tapered structure is not suitable for all the modes for a ring core fiber and a convex core fiber; however, it can be accomplished for multicore fiber and single-core fiber.

Depolarization analysis and compensation in spun birefringent optical fibers with fiber half-wave plate

Abstract: The apparent depolarization occurs when the broadband optical radiation propagates along a Spun Highly Birefringent (SHB) fiber, which will cause a decrease in polarization sensibility as well as the performance of the polarimetric sensor using the fiber. In this paper, a fiber half-wave plate made of the helically wound SHB fiber is used to compensate for the depolarization in the fiber. The half-wave plate is created by winding the SHB fiber around a cylinder and it is located at the midpoint of the whole SHB fiber. Therefore, the half-wave plate is an embedded fiber-based compensation element. The degree of polarization in the SHB fiber has been researched by simulation and experiment. The measured result suggests the excellent performance of our compensation method.

Accurate Measurement and Enhancement of Fiber Coil Symmetry

Abstract: The pure Shupe effect is substantially reduced in a fiber optic gyroscope (FOG) with symmetrical windings. However, the effect of the temperature-induced nonuniformity of the stress in the coil depends on the mean temperature derivative (T-dot). Research on precision winding technology has discovered that the symmetry of optical fiber rings affects the temperature performance of fiber optic gyroscopes. Optical fiber rings with good symmetry also have good temperature performance. This paper first establishes a temperature drift model of optical fiber rings that includes the Shupe effect and T-dot effect and then uses finite element simulation to analyze the drift error of optical fiber rings in a variable temperature environment. Analysis shows that this drift is caused by the variation and uneven distribution of the fiber length and the refractive index in the positive and negative winding of the optical fiber ring, which results in a residual phase difference that is directly related to the symmetry of the optical fiber ring. Simulation and analysis show that balancing the residual phase difference of the optical fiber ring can be achieved by cutting the length of the optical fiber ring at both ends. This paper uses optical frequency domain reflectometry (OFDR) technology to precisely test the symmetry of the optical fiber ring, ensuring accurate adjustment of the lengths at both ends of the optical fiber ring. Experimental tests on two gyroscopes have shown that the optical fiber ring with a smaller drift error can be obtained after testing and adjusting its length. The experimental data indicates that the bias stability of two laboratory gyros are increased by 23.6% and 18.1%, and the bias range are reduced by 22.4% and 30.0%.

An impact-insensitive fiber optic current transformer based on polarization maintaining photonic crystal fiber delay coil

Abstract: When the polarization-maintaining fiber (PMF) delay coil of a fiber optic current transformer (FOCT) is impacted, external forces on the optical fibers and change of their birefringence may lead to extra phase errors during the propagation of optical signals in the fibers. These errors increase the error in current measurement. In the paper, the environmental impact mechanisms influencing the PMF delay coil of FOCT were investigated with a mathematical error model. The method of replacing PMF with a polarization-maintaining photonic crystal fiber (PCF) as the delay coil was proposed. Also, the relationship between structural parameters of air holes and linear birefringence of the polarization maintaining PCF subjected to stress was investigated. The structural parameters of optical fibers were also optimized subsequently. Simulated impact experiments of FOCT with polarization-maintaining PCF and PMF as the delay coil, respectively, demonstrated the effective impact resistance of FOCT with polarization-maintaining PCF delay coil after the optimization of its structural parameters. The current measurement errors of the FOCTs with polarization maintaining PCF delay coil reduced by approximately 35% with respect to the FOCT with PMF delay coil.

57-fs, Er-doped all-fiber all-polarization-maintaining amplifier based on a hybrid DCF/FBG scheme for dispersion compensation

Abstract: In this paper we experimentally demonstrate a femtosecond all-polarization- maintaining laser amplifier in an all-fiber scheme, which consists of a mode-locked oscillator and a two-stage amplifier. A hybrid method of dispersion compensation is proposed based on a dispersion compensation fiber and two fiber Bragg gratings with different group velocity dispersion. The output pulse from the amplifier is 57 fs with average power of 150 mW and repetition rate of 60 MHz, corresponding to peak power of 38.6 kW. By evaluation of pulse shaping, one third of group velocity dispersion in the amplifier was compensated by the pair of gratings, and the remained amount compensated by the dispersion compensation fiber.

Fiber-Based Techniques to Suppress Stimulated Brillouin Scattering

Abstract: Stimulated Brillouin scattering (SBS) is the major factor that limits the maximum optical fiber output power in narrow linewidth applications, which include important fields such as passive optical networks (PONs), high-power fiber amplifiers, and lasers. Great efforts have been dedicated to suppressing the SBS effect and increasing the maximum optical fiber output power. This paper focuses on key fiber-based techniques to suppress SBS. These techniques take advantages of the properties of optical fibers. We present how these properties (electric modes, acoustic modes, and material properties) could be utilized to suppress SBS. The fiber-based techniques are divided into transverse optical fiber design, longitudinal variant fiber design, and external perturbations (strain and temperature) on optical fibers. Transverse optical fiber design focuses on the mechanism electro-acoustic interaction. Large effective area fiber design and acoustic tailoring techniques have been discussed. Longitudinal variant fiber design considers the nonlinear SBS interaction along propagation distance, and various techniques related have been presented. External perturbations (strain and temperature) on optical fibers emphasize on how external static perturbations could modify the SBS effect.

Controllable Light Scattering on Fiber Bragg Gratings in Multimode Fibers: Tailoring Angular Emission for Advanced Fiber-Based Light Sources

Abstract: We study lateral light scattering on fiber Bragg gratings (FBG) with the goal of creating an optical fiber-based linear light source with controllable emission angles. The scattering from two FBGs was measured for polar angles (measured from the fiber axis) in the range θ = 27.1–152.9° and for all azimuth angles around the fiber. The observed light emission is strongly concentrated in one or more scattering cones around the fiber axis, showing four intensity peaks on opposite sides. These scattering phenomena are described and explained using the volume current method. This method shows a novel and simple way to understand the side scattering on FBGs as a combined effect of the grating’s longitudinal period, the grating harmonics, and its transversal shape. Further, this work contributes to a better understanding of the azimuth FBG-scattering caused by an interplay of the transversal grating shape and the fiber modes. The presented method can generate tailored side emissions for fiber light source applications, create light power sensors, or suppress unwanted scattering on FBGs for low optical loss applications.

Orthogonal polarization multi-wavelength Brillouin random fiber laser with triple Brillouin frequency shift space.

Abstract: A novel multi-wavelength Brillouin random fiber laser with the channel space of triple Brillouin frequency shift and high polarization orthogonality between adjacent wavelengths (TOP-MWBRFL), to the best of our knowledge, is experimentally demonstrated. The TOP-MWBRFL is structured in a ring form by cascading two Brillouin random cavities of single-mode fiber (SMF) and one Brillouin random cavity of polarization-maintaining fiber (PMF). Based on polarization pulling properties of stimulated Brillouin scattering in long-distance SMFs and PMFs, the states of polarization (SOPs) of lasing light from SMF random cavities are linearly bounded to the SOPs of local pump light, whereas the SOP of lasing light from the PMF random cavity is strictly clamped on one of the principal axes of the PMF. Thus, the TOP-MWBRFL can stably emit multi-wavelength light with high polarization extinction ratio (>35d B) between adjacent wavelengths without precise polarization feedback. In addition, the TOP-MWBRFL can also work in one polarization mode to stably lase multi-wavelength light with SOP uniformity as high as 37 dB.