Multi-wavelength Brillouin Fiber Laser Research Articles

Polarization Influence on Er3+-Doped Multi-Wavelength Brillouin Fiber Laser Based on Fiber Loop Mirror

Polarization influences on the performance of multi-wavelength Brillouin Er3+-doped fiber laser are investigated by adjusting the polarization controller (PC) in the fiber loop mirror (FLM), where the linear laser cavity is composed of a fiber-tailed mirror and an FLM, and the stimulated Brillouin scattering (SBS) and the Er3+-doped fiber amplification (EDFA) simultaneously serve as the cavity gain. We realized 1–7 Brillouin laser lines by increasing the 980 nm pump power. For the first-order Brillouin laser, the signal–noise ratio (SNR) and optical intensity present a sinusoidal envelope; the conversion efficiency changes significantly from 0.56465 dBm/mw to 0.44975 dBm/mw by adjusting the ring’s angle in the PC; the first-order SBS thresholds are 20.4 mw, 36.1 mw and 28.5 mw at different angles θ2 = 36°, 276° and 300°, respectively; flatness between the two Brillouin lasers change obviously from 2.863 dB to 41.801 dB with different ring angles; the second-order Brillouin laser is suppressed and disappears finally at Δθ2 = −64° to −84° and 106°~136° angle variation. For the fifth-order Brillouin laser, the highest-order Brillouin laser line is seriously suppressed until it disappears at some angle variations similarly. The powers and wavelength stabilities for one-, three- and seven-wavelength Brillouin fiber lasers were measured in 1 h, and the obtained Er3+-doped multi-wavelength Brillouin fiber laser (MWBFL) worked stably during that time, but the stabilities become worse with higher SBS orders.

Multi-wavelength sub-100 Hz linewidth Brillouin fiber laser with cascaded SBS polarization parity-time symmetry

A multi-wavelength sub-100 Hz linewidth Brillouin fiber laser (BFL) with cascaded stimulated Brillouin scattering (SBS) polarization parity-time (PT) symmetry is proposed and experimentally investigated. Multi-order Stokes wave generation using a structure consisting of a main fiber ring (MFR) and a sub fiber loop (SFL). The MFR is used to excite the Stokes laser and to guarantee single longitudinal mode (SLM) operation of the generated stokes laser of each order and the SFL cascades each Stokes lasing emission to act as a Brillouin pump for the next order of Stokes generation. A Sagnac loop in the MFR consisting of optical coupler (OC), polarization beam splitter (PBS) and two polarization controllers (PCs), is used to achieve cascaded SBS polarization PT symmetry. By tuning the PC to control the polarization state of each order linearly polarized light injected into PBS at each order, thus controlling the gain and loss of the loop corresponding to the two backpropagating light waves. When the gain and loss of the coupling loops are the same in magnitude and greater than the coupling coefficient, the cascaded SBS polarization PT symmetry is broken, resulting in SLM operation for each order of Stokes waves. Experimental results reveal that thirteen Stokes waves were obtained from two different output ports at an erbium-doped fiber amplifier (EDFA) output power of 28 dBm. The measured linewidths at — 20 dB power were 0.34, 0.39, 0.33, 0.4, 0.39 and 0.43 kHz for the 1st-6th order Stokes emission, corresponding to linewidths of 17.1, 19.6, 16.6, 20.1 19.6 and 21.6 Hz, respectively, while the maximum side mode suppression ratios (SMSRs) were measured to be 47, 45, 49, 44, 41 and 41 dB for the 1st-6th order Stokes emission. Within 60 min of the stability experiment, the wavelength and power stability were ±2 pm and ±0.6 dB, respectively. Compared with previous studies, the present design guarantees the operation of SLM for each order of Stokes waves with sub-100 Hz laser linewidth.

Wideband multiwavelength Brillouin fiber laser with switchable channel spacing.

A multiwavelength Brillouin fiber laser (MBFL) with a switchable channel spacing is demonstrated using a 1.55-µm single-mode AlGaInAs/InP hybrid square-rectangular laser as a seeding source. The scheme employs a highly nonlinear fiber loop with a feedback path to generate a 10-GHz-spacing MBFL. Then, assisted by a tunable optical bandpass filter, MBFLs with spacing from 20GHz to 100GHz at a step of 10GHz are generated in another highly nonlinear fiber loop based on the cavity-enhanced four-wave mixing. More than 60 lasing lines with an optical signal-to-noise ratio over 10dB are obtained successfully in all the switchable spacings. The total output power and the channel spacing of the MBFLs are proved to be stable.

Advances in multi-wavelength Brillouin fiber lasers: An outlook across different spectral regions

In recent years, Brillouin fiber lasers have become a promising optical source technology for academic and industrial purposes. Among the promising laser solutions that have emerged with low threshold, high efficiency, small linewidth, and low resonator loss, multi-wavelength architecture has attracted the most attention recently. However, the development of configurations with an increased number of Stokes channels that present high flatness and reasonable optical-to-signal ratio (OSNR) is a challenge that this fiber laser technology still faces, and the development of solutions for this is an open problem. From this perspective, this paper presents a review focused on recent progress in multi-wavelength Brillouin fiber laser (MBFL) devices. Specifically, microwave generation and temperature sensing applications are discussed. Key results in the spectral regions of 1.0μm, 1.3μm, 1.5μm, 1.6μm, and 2.0μm are reported, as well as future perspectives are addressed in this review for the advancements in multi-wavelength fiber laser sources.

A multi-wavelength Brillouin fiber laser of switchable frequency spacing based on a bi-directional ring cavity

A multi-wavelength Brillouin fiber laser (MW-BFL) of switchable frequency spacing is proposed and experimentally demonstrated. This MW-BFL comprises a ring cavity that includes a piece of 20-km-long single-mode fiber as the gain medium for Brillouin amplification. The switchability of wavelength spacing is implemented by adjusting the Brillouin pump (BP) coupling ratio into the ring cavity of a bi-directional pumping scheme, as the outputs of single and double Brillouin shifts are achieved with either a 50/50 coupler or a 99/1 coupler, respectively. A total of 11 lasing Stokes lines with single Brillouin shifts and 9 lasing Stokes lines with double Brillouin shifts have been observed when the BP power is set at 0 dBm. Both Brillouin lasers are wavelength-tunable, and the tuning ranges are 16 and 10 nm for the single- and double-spaced outputs, respectively.

The experimental study on pump influence of a multi-wavelength Brillouin fiber laser with switchable frequency spacing

An experimental study of the pump influence upon a multi-wavelength Brillouin fiber laser (MW-BFL) of switchable Brillouin Stokes generation is presented. The bi-directional ring cavity in the MW-BFL is comprised of a piece of 20-km single-mode fiber to provide the Brillouin gain. We investigate the major pump parameters including the Brillouin pump (BP) ratio into the ring cavity, the initial BP power, and the primary pump power for their effectiveness on the switchable-spaced Brillouin generation. The optical signal to noise discrepancy (OSNRD) between the adjacent odd and even Stokes lines is evaluated as the main indicator. The optimal BP coupling ratio is found as 90/10 for the proposed scheme. Four Brillouin lasing lines with single frequency shift of 10.75 GHz and one Brillouin lasing line with double Brillouin shift of 21.51 GHz have been observed when the input BP power is at −5 dBm and 4 dBm, respectively. An appreciable OSNRD is obtained accordingly, which is 0.6 dB for the single-spaced spectrum and 18.6 dB for the double-spaced spectrum.

A low-threshold multiwavelength Brillouin fiber laser with double-frequency spacing based on a small-core fiber* *Project supported by the National Natural Science Foundation of China (Grant No. 61875094), China Postdoctoral Science Foundation (Grant No. 2018M642386), and K. C. Wong Magna Fund in Ningbo University.

We demonstrate multiwavelength Brillouin fiber lasers (MWBFLs) with double-frequency spacing based on a small-core fiber (SCF) and a standard single-mode fiber (SMF), which have core diameters of 5 and 8.8 μm, respectively. Experimental results show that the SCF-based MWBFL exhibits a higher laser output power and a lower pump threshold. The output powers of the SCF-based MWBFL are > 1.4 times those of the SMF-based MWBFL. Moreover, the threshold power required to generate each channel of the SCF-based MWBFL is 59% that of the SMF-based MWBFL. When the same pump power of 180 mW is injected, the number of laser channels generated for the SCF-based MWBFL is 13, which is twice that generated for the SMF-based MWBFL. In addition, the SCF-based MWBFL exhibits good wavelength tunability from 1535 to 1565 nm and temporal stability over an hour.

Multiwavelength Brillouin Generation in Bismuth-Doped Fiber Laser With Single- and Double-Frequency Spacing

Multiwavelength fiber lasers operating in the 1.3 μm wavelength region are of great interest as they complement existing systems in the conventional optical communication band of 1.55 μm. In this work, a multiwavelength Brillouin fiber laser with single- and double-Brillouin frequency spacings operating in 1.3 μm is proposed and demonstrated using a dispersion compensating fiber (DCF) as the Brillouin gain medium. A bismuth-doped fiber serves as the laser gain medium. At the maximum pump power of 1021 mW and with the Brillouin pump set at 11 dBm, up to 7 Brillouin Stokes lines with a wavelength spacing of 0.074 nm are obtained in the single-spaced configuration. In the case of the double-spaced configuration, 14 Stokes lines are generated with a wavelength spacing of 0.15 nm between the even Stokes lines. By tuning the central wavelength of the Brillouin pump, both laser configurations are wavelength-tunable with a range of 93 nm and 19 nm for the single-spaced and double-spaced Brillouin lasers respectively. This is, to the best of the author's knowledge, the first demonstration of a multiwavelength/Brillouin laser using a bismuth-doped fiber as the laser gain medium.

Wideband multiwavelength Brillouin fiber laser based on dual-mode AlGaInAs/InP microcavity lasers

A multiwavelength Brillouin fiber laser (BFL) is demonstrated using a 1.55-µm AlGaInAs/InP microcavity laser as a seed source. The combination of a nonlinear fiber cavity and a feedback loop leads to multiwavelength generation with a channel spacing of double-Brillouin-frequency assisted by cavity-enhanced four-wave mixing. The amplified output of a dual-mode lasing square microcavity laser with a wavelength interval of 1.5 nm is applied as the pump source for the broadband multiwavelength generation. A wideband multiwavelength BFL covering from 1490 nm to 1590 nm is successfully generated at an optimized pump power of 25 dBm and a feedback power of -17.2dBm. The power stability of 0.82 dB over a 60 min duration of the multiwavelength BFL can satisfy the demands for the optical fiber sensing and microwave photonic systems.

Temperature sensing system with high signal-to-noise ratio and large temperature sensing range based on multiwavelength Brillouin fiber laser

A double-ring resonator temperature sensing system based on a multiwavelength Brillouin fiber laser (MBFL) is proposed and demonstrated experimentally. In the two ring resonators, a 3.2-km long dispersion shifted fiber is used as the sensing fiber while a 3.2-km long dispersion compensating fiber is the reference. Second-order Stokes light generated by two gain fibers are used as the beat frequency to obtain the microwave signal. The frequency of the signal is 1.657 GHz, which avoids the low frequency noise region, and the signal has a high signal-to-noise ratio of 39 dB. A change in the center frequency of the beat frequency microwave signal accurately corresponds with the temperature changing. The sensitivity of temperature is 2.26 MHz / ° C in the condition of the sensing temperature being from 5°C to 85°C and the reference temperature being 25°C. Obviously, the MBFL can sense temperature not only below the reference but also above it; thus the scheme has a larger temperature sensing range.

Multi-wavelength Brillouin-erbium fiber laser with more than 95 lines based on a dual-ring structure

We demonstrate a multi-wavelength Brillouin fiber laser based on a dual-ring structure to take advantage of the forward and backward Brillouin gain simultaneously with an injected tunable scanning lasing. We used two erbium-doped fiber amplifiers for the amplification of the seed lasing and the operated Brillouin laser. The cascaded stimulated Brillouin effect in the section of dispersion-shifted fiber contributes to the free oscillation suppression in cavity. When the laser operates at the center wavelength of 1565 nm, the output spectra shows the maximum Brillouin lines of more than 95 with a wavelength spacing of about 0.08 nm under the maximum pump. Through adjusting of the seed wavelength and the tunable filter in cavity, the output spectra can be shifted from 1540 to 1570 nm. This fiber laser will find potential applications in optical measurement and sensing because of its large line number, stability, tunability and fixed wavelength spacing.

A compact linear-cavity multi-wavelength Brillouin/thulium fiber laser in S/S+-band

• A compact Brillouin laser linear cavity system. • Multi-wavelength output over a 55 nm tuning range from 1460 to 1515 nm. • 28 Brillouin Stokes lines generated at maximum pump power of 250 mW. • Also covers the S + -band region with 5 Stokes lines. A compact Brillouin thulium-doped fluoride fiber (TDFF) multi-wavelength fiber lasers (MWFLs) operating in the S/S + band region is proposed and demonstrated. The system is based on a linear design and utilizes two Faraday mirrors at both ends of the cavity to enable bi-directional oscillation. An 11.5 m long TDFF with an absorption rate of 0.15 dB/m at 1400 nm is used as the gain medium. A stable output laser comb with 28 Stokes lines is obtained at the maximum pump power of 250 mW at the wavelength of 1488 nm. The multi-wavelength Brillouin fiber laser can also be tuned, covering a total tuning range of 55 nm from 1460 nm to 1515 nm. The proposed system is highly stable, and would have significant practical applications.

High sensitive temperature sensing system based on multi-wavelength fiber laser with dispersion shifted fiber

A temperature sensing system based on a multi-wavelength Brillouin fiber laser (MBFL) is proposed and demonstrated. Two beams of Stokes light are generated in a temperature sensitive fiber and a reference fiber, respectively. Stokes light from temperature sensitive fiber can generate frequency shift with temperature changing, and two beams can produce a microwave signal by beat frequency. Therefore, change of temperature can be accurately measured according to variation of the central frequency of the beat frequency microwave signals. A 3.2 km long dispersion shifted fiber (DSF) is used as temperature sensitive fiber pumped by a Brillouin pump with power of 1.5 W, then more than 20 Stokes light wavelengths can be observed. By using the 18th order Stokes light pair, temperature sensitivity can be 19.93 MHz∕°C. The uncertainty of the temperature measurement is ± 0.125°C.

Temperature sensing characteristics based on multi-wavelength Brillouin fiber laser

Temperature sensing characteristics based on multi-wavelength Brillouin fiber laser

Fiber bragg grating assisted cavity loss reduction in the generation of multiwavelength brillouin fiber laser

This work investigates two types of multiwavelength Brillouin fiber laser configurations. These configurations are ring-cavity multi-wavelength Brillouin fiber laser employs fiber Bragg grating and S-shaped multiwavelength Brillouin fiber laser. The two arrangements comprise of 10km long single mode fiber as a gain medium and operate in the C-band region. Replacing the S-Shaped with Bragg grating fiber has led to a loss reduction in the ring-cavity multiwavelength Brillouin fiber laser and subsequently generated higher number Brillouin Stokes (BS) signals. The maximum of 33 BS signals with ∼0.08nm (∼10GHz) spacing is obtained. Optical signal to noise ratio of about 15dB is observed at output coupling ratio of 70%, when 1550nm of Brillouin pump is launched into the ring-cavity multiwavelength Brillouin fiber laser employs fiber Bragg grating. In contrast, due to the limitation of high cavity losses, only 17 BS signals with ∼0.16 (20GHz) spacing are generated from the S-shaped multi-wavelength Brillouin fiber laser. These findings contribute new insights and profiles of the multi-wavelength Brillouin fiber laser employs fiber Bragg grating that has the capability to reduce cavity losses while generating a high number of Brillouin Stokes signals.

Triple Brillouin frequency spacing multiwavelength fiber laser with double Brillouin cavities and its application in microwave signal generation

We propose and experimentally investigate a multiwavelength Brillouin fiber laser (MBFL) with triple frequency spacing by employing a modular structure. In this scheme, we obtain nine channels optimized with frequency spacing of 0.259 nm. The single, double, and triple Brillouin frequency spacing for the MBFL can be easily realized by utilizing this modular structure. The impact of Brillouin pump (BP) power, BP wavelength, and erbium-ytterbium-doped fiber amplifier (EYDFA) output power on the performance of the MBFL is investigated, respectively. We also study the generation of beating frequency microwave signals based on single, double, and triple frequency spacing MBFL. 10.5 GHz, 21.48 GHz, and 31.77 GHz microwave signals with 3 dB linewidth of 16.4 MHz, 15.2 MHz, and 12.8 MHz are generated, respectively.

Multiple lasing Brillouin Fiber Laser with the implementation of reflective Fiber Bragg Grating in a ring cavity configuration

A multi-wavelength Brillouin fiber laser with the implementation of reflective fiber Bragg grating is developed. In this ring cavity architecture, the fiber laser system is performed by the stimulated Brillouin scattering effect and four-wave mixing process. An improvement in the number Brillouin Stokes signal and average of the optical signal to noise ratio were generated through the reflection process of fiber Bragg grating. Due to the optimization of output coupling ratio from 10% to 60%, the highest Brillouin Stokes signal of 17 and average optical signal to noise ratio of 14.7 dB were recorded at 60% of the output coupling ratio. The amplified Brillouin pump power of 16.5 dBm at 1550 nm of Brillouin pump wavelength was injected into the laser system. A constant line spacing of 0.08 nm at each of the Brillouin Stokes signals was also recorded.

Loop Mirror Multi-wavelength Brillouin Fiber Laser Utilizing Semiconductor Optical Amplifier and Fiber Bragg Grating

In this paper, the development of loop mirror multi-wavelength Brillouin fiber laser utilizing semiconductor optical amplifier and fiber Bragg grating is successfully demonstrated. A multi-wavelength BFL structure employs a single mode fiber that acts as the gain medium, while the fiber Bragg grating act to reflect the signals and semiconductor optical amplifier is used to amplify the signal are employed to produce multiple channels. The implementation of difference parameter for semiconductor optical amplifier driven current, Brillouin pump power, Brillouin pump wavelength and length of single mode fiber, plays an important role in producing the multiple channels. The highest number of channels which is 15 achieved once 9 km of SMF length, semiconductor optical amplifier current at 800mA and low Brillouin pump power at -12 dBm are utilized in the laser structure. Furthermore, the implementation of semiconductor optical amplifier and reflectivity of fiber Bragg grating in Brillouin fiber laser structure gives a better performance in producing the multiple channels.

Lasing characteristics of 10 GHz signal spacing in a ring cavity multi-wavelength Brillouin fiber laser employing fiber Bragg grating

This paper experimentally demonstrated a ring cavity multi-wavelength Brillouin fiber laser employing fiber Bragg grating (FBG) that operated in the C-band region. The FBG plays a significant role to reflect signals and filter selected wavelengths. A number of generated Brillouin Stokes (BS) signals and tuning range ability were investigated. A 9[Formula: see text]km length of single mode fiber was utilized to provide a Brillouin gain medium for generating stimulated Brillouin scattering effect. In this work, at optimum output coupling ratio of 90% and Brillouin pump (BP) wavelength of 1550[Formula: see text]nm, up to a maximum of 26 BS signals were recorded by injecting 63.1[Formula: see text]mW of amplified BP powers. The BS signals were also tunable within the ranges of 1544–1556[Formula: see text]nm in accordance with the FBG properties at 3[Formula: see text]dBm bandwidth of 5[Formula: see text]nm.

Enhanced multiwavelength generation in Brillouin fiber laser with pump noise suppression technique

A new multiwavelength Brillouin fiber laser (BFL) that provides a large number of Stokes lines with improved optical signal-to-noise ratio has been proposed and demonstrated. The BFL cavity is only formed by a nonlinear fiber loop mirror (NOLM) with 500 m long highly nonlinear fiber (HNLF). The BFL with improved performance is based on the suppression of the Brillouin pump noise floor utilizing a narrow tunable bandpass filter. The generation of Stokes lines covering up to a 33.67 nm wavelength range is achieved by setting the Brillouin pump signal within the HNLF’s zero dispersion wavelength and with power of 250 mW. This is owing to the combination of the stimulated Brillouin scattering and four-wave mixing effect in the NOLM structure.