Tunable Dual-wavelength Fiber Laser Research Articles

Switchable and tunable dual-wavelength thulium-doped fiber laser based on the parallel filter of the all-fiber Sagnac interferometer embedded with an FBG and the Fabry-Perot filter

A switchable and tunable dual-wavelength thulium-doped fiber laser (ST-DW-TDFL) based on the parallel filter is proposed and experimentally demonstrated in this study. In the proposed ST-DW-TDFL, there are two independent branches to form the parallel filter. One branch uses an all-fiber Sagnac interferometer embedded with a fiber Bragg grating (FBG-FSI) as the wavelength selection element, and the other branch uses a Fabry-Perot (FP) filter as the wavelength selection element. By adjusting two optical attenuators to change the light power of two branches, single and dual-wavelength output can be achieved and switched. On the basis of achieving dual-wavelength output, independent and continuous tuning of two wavelengths can be achieved by heating the FBG and adjusting the FP filter. The tuning range of one wavelength is up to 5.84 nm, while the tuning range of the other wavelength is up to 99.86 nm. The maximum wavelength variation and power fluctuation are less than 0.03 nm and 0.5 dB at room temperature. And the experimental results show that the proposed ST-DW-TDFL has flexible wavelength switching and tuning capabilities and good wavelength and power stabilities.

Tunable wide spacing all-fiber dual-wavelength holmium-doped fiber laser using a Lyot filter operating above 2 µm

In this work, we successfully demonstrated an all-fiber, dual-wavelength holmium-doped fiber laser (HDFL) with a tunable wavelength spacing range of 8 nm to 24 nm. The HDFL utilizes a Lyot filter to obtain a stable dual wavelength output, with the Lyot filter being constructed from a polarizer, a 20 m polarizing maintaining fiber (PMF) and two polarization controllers (PCs). The dual-wavelength HDFL has an operating wavelength range from 2072.1 nm to 2097.2 nm and a maximum spacing of 24 nm between the lasing wavelengths as well as a signal-to-noise ratio of up to 45 dB and a side mode suppression ratio as low as 0.15 dB. The HDFL is highly stable, with the lasing output have a low power fluctuation of only 2.3 dB over a continuous operation period of 75 min. The proposed HDFL would have substantial applications as a low cost laser source for sensing applications beyond the 2 µm region, particularly those that require a control signal.

Broadly tunable dual-wavelength thulium-doped fluoride fiber laser covering S-band region from 1472 to 1506 nm

Dual-wavelength fiber lasers have gained the interest of researchers in practical applications such as fiber-optic sensors and optical telecommunication. This work demonstrated a broadly tunable dual-wavelength thulium-doped fluoride fiber laser (TDFFL) at the S-band region. Two tunable-bandpass filters (TBPFs) were incorporated in the TDFFL cavity to achieve dual-wavelength fiber laser (DWFL) operation. Two identical peaks with a balanced signal-to-noise ratio (SNR) were acquired by tuning TBPFs and an attenuator within the cavity. The DWFL covers a significant portion of S-band TDFFL gain from 1472.9 to 1506.5 nm with a wide tunability in wavelength spacing from 0.95 to 33.6 nm. The narrowest possible DWFL was achieved with the spacing of 0.95 nm at the operating wavelengths of 1489.2 and 1490.15 nm, with a frequency bandwidth of 128 GHz. The broadest spacing of 33.6 nm was achieved at operating wavelengths of 1472.9 and 1506.5 nm, with a frequency bandwidth of 4.79 THz.

All-normal dispersion widely tunable dual-wavelength mode-locked fiber laser based on NALM.

We experimentally and numerically demonstrate the all-normal dispersion (ANDi) ytterbium (Yb)-doped fiber laser based on nonlinear amplifying loop mirror (NALM) mode-locked, which allows tunable single-wavelength and dual-wavelength outputs. The pulses tuning ranges of the dual-wavelength are from 1032.24 nm to 1053.13 nm and from 1047.94 nm to 1069.05 nm, and the repetition frequency difference varies from 1766Hz to 1834Hz. To our knowledge, this is the widest dual-wavelength tuning range of Yb-doped fiber lasers based on NALM mode-locked. We test for 90 minutes and have high stability in both single-wavelength and dual-wavelength. In addition, the pulsed collision dynamics between two solitons at different wavelengths are numerically studied. Numerical results show that during the pulse collision, the two solitons pass through each other and maintain their properties, which also confirms the particle nature of the isolated wave. Our research contributes to the dynamics of dual-wavelength solitons collision in NALM mode-locked fiber laser and provides what we believe to be is a new idea for tunable Yb-doped dual-comb sources.

Responsiveness of temperature using tunable dual-wavelength Q-switched fiber laser

In this paper, a responsiveness temperature based on a tunable dual-wavelength Q-switched fiber laser has been proposed and experimentally demonstrated. Experiments have been carried out with tunable dual-wavelength Q-switched fiber laser by using graphite as a saturable absorber, which is incorporated in the two fiber Bragg gratings (FBG) as a sensing element. Both FBG 1 and FBG 2 have a central wavelength of 1550 nm and 1551 nm, respectively. The optical spectral and RF signals are proven observed during the temperature change. The results from optical spectra demonstrate the measured temperature has good linearity, where the slope of the graph is thus the temperature sensitivity of 1550 nm FBG. The R2 value of the graph is 0.965 and the value of temperature sensitivity is 0.0064 nm °C−1. For FBG 2 as the sensing element, the R2 value of the graph is 0.9751 and the value of temperature sensitivity is 0.0068 nm °C−1. In addition, the repetition rate is almost linear with the temperature change, giving the correlation factor of R2 value of FBG 1 and FBG 2 are 0.8118 and 0.9046, respectively. The experimental results prove the feasibility of the proposed temperature sensor.

Tunable and switchable dual-wavelength SLM narrow-linewidth fiber laser with cascaded passive double-ring cavity narrowband filters

In this article, we have proposed and demonstrated a tunable, switchable dual-wavelength linear cavity fiber laser, which has a passive dual ring cavity structures (DRCs) and polarization-maintaining fiber Bragg grating (PM-FBG), and can be used for the operation of single-longitudinal mode(SLM), narrow-linewidth, and orthogonal single polarization. The passive DRCs, consisted of four 2 × 2 optical couplers (OCs), work as the narrow-band filter and mirror. The tunable and switchable wavelength of the fiber laser is realized by stretching PM-FBG and adjusting the polarization controller (PC). The optical signal-to-noise ratio (OSNR) at the dual-wavelength operating state can be more than 45 dB in the tunable range. While the OSNR of fiber laser at the each-wavelength operating state can reach 50 dB with the maximum wavelength and power fluctuation of 0.01 nm and 1.2 dB, during the monitoring time of 40 min. In addition, the measured laser linewidths are 375 Hz and 420 Hz, respectively. Meanwhile, the states of polarization are orthogonal single polarization, and the degree of polarization (DOP) is close to 100 %.

Tunable Dual-Wavelength Fiber Laser in a Novel High Entropy van der Waals Material

Fiber lasers with different net dispersion cavity values can produce some types of solitons, and rich nonlinear dynamics phenomena can be achieved by selecting different saturable absorbers. A new layered high-entropy van der Waals material (HEX) (Mn,Fe,Co,Ni)PS3 was selected as a saturable absorber to achieve a high-power laser output of 34 mW. In addition, the wavelength can be dynamically tuned from 1560 nm to 1531 nm with significant dual-wavelength phenomena at 460 fs pulse duration.

Widely Tunable Narrow Linewidth Dual-Wavelength Yb-Doped Fiber Laser With Inhomogeneous Polarization Output

We demonstrate a widely tunable narrow linewidth dual-wavelength Yb-doped fiber laser with switchable inhomogeneous polarization output based on the Pancharatnam-Berry phase optical elements and volume Bragg grating experimentally. By rotating the Glan laser polarizer, we can obtain the switchable radially and azimuthally polarized beam with tunable wavelength separation ranging from 0.4 nm to 68.2 nm. The delivered spectrum shows excellent stability and linewidth narrower than 0.08 nm. Moreover, the polarization extinction ratio of the radially and azimuthally polarized beam can reach 94.2% and 93.6%, respectively. This tunable narrow linewidth dual-wavelength laser could enrich the manipulation potential of the fiber laser, and would benefit many applications like THz wave generation.

Tunable and Switchable Dual-Wavelength SLM Narrow-Linewidth Fiber Laser with a PMFBG-FP Filter Cascaded by Multi-Ring Cavity

A single longitudinal mode (SLM) dual-wavelength switchable erbium-doped fiber laser (DW-EDFL) based on polarization-maintaining fiber Bragg grating Fabry–Perot cavity (PMFBG-FP) cascaded multiple sub-ring cavities (MSCs) is proposed. A PMFBG-FP with a narrow-band transmission peak and MSCs was implemented as an optical filter to achieve stable dual-wavelength laser output and guaranteed SLM status. By stretching the PMFBG, a highly stable dual-wavelength tunable output could be achieved with a maximum tuning interval of 0.17 nm. The optical signal-to-noise-ratio (OSNR) at dual-wavelength lasing was higher than 57 dB, and the optimal wavelength and power fluctuations within 0.5 h were 0.01 nm and 0.79 dB, respectively. Meanwhile, the measured linewidths of each wavelength were 1.55 kHz and 1.65 kHz, respectively. The measured polarization states of the two laser wavelengths were linear and orthogonal, with a degree of polarization (DOP) of nearly 100%.

Sideband-free tunable and switchable dual-wavelength mode-locked fiber laser based on the Lyot filter and spontaneous radiation peaks.

We demonstrate a compact tunable and switchable dual-wavelength fiber laser based on the Lyot filtering effect and the spontaneous radiation peaks of gain fiber. By introducing a period of polarization-maintain Er-doped fiber (PM-EDF), stable dual-wavelength pulses can operate in both the anomalous dispersion region and the normal dispersion region. The corresponding repetition frequency difference of the dual wavelengths has excellent stability while the relative center wavelength can be adjusted in the range of 5 nm to 13 nm. There is no existence of significant sidebands in the optical spectrum during the whole tuning process. This dual-wavelength laser based on two spontaneous radiation peaks in the shorter wavelength direction has great application potential. Our work provides a new design solution for dual-comb sources (DCSs).

Tunable Spacing Dual-Wavelength Q-Switched Fiber Laser Based on Tunable FBG Device

A tunable spacing dual-wavelength Q-switched fiber laser is experimentally demonstrated based on a fiber Bragg grating tunable device incorporated in an erbium-doped fiber laser (EDFL). The system utilizes two identical fiber Bragg gratings (FBGs) at 1547.1 nm origin to enable two laser lines operation. The wavelength separations between two laser lines are controlled by fixing one of the FBGs while applying mechanical stretch and compression to the other one, using a fiber Bragg grating tunable device. The seven steps of wavelength spacing could be tuned from 0.3344 to 0.0469 nm spacing. Pulse characteristics for both close and wide spacing of dual-wavelength Q-switched fiber laser are successfully being recorded. The findings demonstrate the latest idea of dual-wavelength fiber laser based on FBG tunable device, which offers a wide range of future applications.

Tunable Dual-Wavelength Bismuth Fiber Laser With 37.8-GHz Frequency Spacing

A tunable dual-wavelength Brillouin-bismuth fiber laser with a triple-Brillouin frequency spacing of ∼37.8 GHz was demonstrated by employing modular structures. The modular designs can be divided into two main cavities, whereby cavity 1 consisted of a 2-km single-mode fiber (SMF) and a loop mirror that was able to generate a single-spaced Brillouin shift, while cavity 2 comprised of 10-km dispersion compensating fiber (DCF) that was able to produce a double-spaced Brillouin shift. Based on this design, a stable dual-wavelength lasing was established with a low peak power fluctuation of 0.13 dB and 0.6 dB for the Brillouin pump (BP) and third Brillouin Stokes line (BS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ), respectively. By varying the center wavelength of the Brillouin pump, the dual-wavelength laser can be tuned across a 40 nm span, ranging from 1300 nm to 1340 nm. The frequency spacing of the Brillouin-bismuth fiber laser can also be easily switched between ∼12.6 GHz, ∼25.2 GHz, and ∼37.8 GHz by utilizing these modular structures. The proposed dual-wavelength laser has a promising potential for application as a low phase noise source for microwave generation.

A 70 W thulium-doped all-fiber laser operating at 1940 nm

An all-fiber thulium-doped fiber laser operating at a wavelength of 1940 nm is reported. A maximum output continuous-wave power of 70.7 W with a slope efficiency of 59%, determined with respect to the absorbed pump power, was demonstrated. The laser delivered almost a single-mode beam with a beam quality factor of &lt; 1.3.Full Text: PDF ReferencesM. N. Zervas and C. A. Codemard, "High Power Fiber Lasers: A Review", IEEE J. Sel. Top. Quantum Electron. 20, 0904123 (2014). CrossRef D. J. Richardson, J. Nilsson, and W. A. Clarkson. "High power fiber lasers: current status and future perspectives [Invited]", J. Opt. Soc. Am. B 27, B63 (2010). CrossRef J. Swiderski, A. Zajac, and M. Skorczakowski, "Pulsed ytterbium-doped large mode area double-clad fiber amplifier in MOFPA configuration", Opto-Electron. Rev. 15, 98 (2007). CrossRef M. Eckerle et al. "High-average-power actively-modelocked Tm3+ fiber lasers", Proc. SPIE 8237, 823740 (2012). CrossRef J. Swiderski, D. Dorosz, M. Skorczakowski, and W. Pichola, "Ytterbium-doped fiber amplifier with tunable repetition rate and pulse duration", Laser Phys. 20, 1738 (2010). CrossRef P. Grzes and J. Swiderski, "Gain-Switched 2-μm Fiber Laser System Providing Kilowatt Peak-Power Mode-Locked Resembling Pulses and Its Application to Supercontinuum Generation in Fluoride Fibers", IEEE Phot. J. 10, 1 (2018). CrossRef S. Liang et al. "Transmission of wireless signals using space division multiplexing in few mode fibers", Opt. Express 26, 6490 (2018). CrossRef J. Swiderski, M. Michalska, and P. Grzes, "Broadband and top-flat mid-infrared supercontinuum generation with 3.52 W time-averaged power in a ZBLAN fiber directly pumped by a 2-µm mode-locked fiber laser and amplifier", Appl. Phys. B 124, 152 (2018). CrossRef F. Zhao et al. "Electromagnetically induced polarization grating", Sci. Rep. 8, 16369 (2018). CrossRef J. Sotor et al. "Ultrafast thulium-doped fiber laser mode locked with black phosphorus", Opt. Lett. 40, 3885 (2015). CrossRef M. Olivier et al. "Femtosecond fiber Mamyshev oscillator at 1550 nm", Opt. Lett. 44, 851 (2019). CrossRef J. Swiderski and M. Michalska, "Over three-octave spanning supercontinuum generated in a fluoride fiber pumped by Er &amp; Er:Yb-doped and Tm-doped fiber amplifiers", Opt. Laser Technol. 52, 75 (2013). CrossRef C.Yao et al. "High-power mid-infrared supercontinuum laser source using fluorotellurite fiber", Optica 5, 1264 (2018). CrossRef J. Swiderski and M. Maciejewska, "Watt-level, all-fiber supercontinuum source based on telecom-grade fiber components", Appl. Phys. B 109, 177 (2012). CrossRef O. Traxer and E. X. Keller, "Thulium fiber laser: the new player for kidney stone treatment? A comparison with Holmium:YAG laser", World J. Urol., 1-12 (2019). CrossRef M. Michalska, et al. "Highly stable, efficient Tm-doped fiber laser—a potential scalpel for low invasive surgery", Laser Phys. Lett. 13, 115101 (2016). CrossRef R. L. Blackmon et al. "Thulium fiber laser ablation of kidney stones using a 50-μm-core silica optical fiber", Opt. Eng., 54, 011004 (2015). CrossRef A. Zajac et al. "Fibre lasers – conditioning constructional and technological", Bull. Pol. Ac.: Tech. 58, 491 (2010). CrossRef C. Guo, D. Shen, J. Long, and F. Wang, "High-power and widely tunable Tm-doped fiber laser at 2 \mu m", Chin. Opt. Lett. 10, 091406 (2012). CrossRef F. Liu et al. "Tandem-pumped, tunable thulium-doped fiber laser in 2.1 μm wavelength region", Opt. Express 27, 8283 (2019). CrossRef H. Ahmad, M. Z. Samion, K. Thambiratnam, and M. Yasin, "Widely Tunable Dual-Wavelength Thulium-doped fiber laser Operating in 1.8-2.0 mm Region", Optik 179, 76 (2019). CrossRef N. M. Fried, "Thulium fiber laser lithotripsy: An in vitro analysis of stone fragmentation using a modulated 110‐watt Thulium fiber laser at 1.94 µm", Lasers Surg. Med. 37, 53 (2005). CrossRef N. M. Fried, "High‐power laser vaporization of the canine prostate using a 110 W Thulium fiber laser at 1.91 μm", Lasers Surg. Med. 36, 52 (2005). CrossRef E. Lippert et al. "Polymers Designed for Laser Applications-Fundamentals and Applications", Proc. SPIE 6397, P639704 (2006). CrossRef N. Dalloz et al. "High power Q-switched Tm3+, Ho3+-codoped 2μm fiber laser and application for direct OPO pumping", Proc. SPIE 10897, 108970J (2019). CrossRef N. J. Ramírez-Martinez, M. Nunez-Velazquez, A. A. Umnikov, and J. K. Sahu, "Highly efficient thulium-doped high-power laser fibers fabricated by MCVD", Opt. Express 27, 196 (2019). CrossRef T. Ehrenreich et al. "1-kW, All-Glass Tm:fiber Laser", Proc. SPIE 7580, 758016 (2010). DirectLink L. Shah et al. "Integrated Tm:fiber MOPA with polarized output and narrow linewidth with 100 W average power", Opt. Express 20, 20558 (2012). CrossRef H. Zhen-Yue, Y. Ping, X. Qi-Rong, L. Qiang, and G. Ma-Li, "227-W output all-fiberized Tm-doped fiber laser at 1908 nm", Chin. Phys. B 23, 104206 (2014). CrossRef

Widely tunable Q-switched dual-wavelength synchronous-pulsed Tm-doped fiber laser emitting in the 2 μm region.

We demonstrate a widely tunable Q-switched dual-wavelength fiber laser emitting synchronized pulses in the 2μm spectral range. Owing to the use of a Tm-doped rod-type fully aperiodic large pitch fiber, together with an acousto-optic modulator and two volume Bragg gratings (VBGs), the wavelength separation was shown to be continuously tunable from 1 to 120nm (∼0.1-10 THz). A peak power higher than 8kW was demonstrated over the whole tuning range for a repetition rate (RR) of 1KHz and a 26ns pulse duration. The RR was modulated from 1 to 30kHz, and the laser pulse duration measured between 23ns and 130ns, depending on the RR and the wavelength separation.

Widely Tunable Dual-Wavelength Fiber Laser in the 2 μm Wavelength Range

In this paper, we demonstrate a widely tunable dual-wavelength fiber laser, which is based on a thulium-doped fiber and volume Bragg gratings triggering the emission wavelengths in the 2-μm band. A continuously tunable wavelength separation range (Δλ), from 1 to 144 nm (0.08–11.47 THz) is demonstrated, with > 4.5 W of output power over the tuning range. The laser emission exhibits a linewidth (FWHM) lower than 0.1 nm independent from wavelengths and Δλ, with more than 45 dB of a signal-to-noise contrast. A maximum output power of 7 W is obtained for shorter Δλ (1–14 nm), corresponding to a slope efficiency of 33% with respect to the incident pump power at 790 nm.

Dual-wavelength Brillouin-erbium fiber laser with tunable wavelength spacing

Abstract A novel wavelength-spacing tunable dual-wavelength Brillouin-erbium fiber laser is proposed and demonstrated experimentally. The dual-wavelength lasing is achieved by combining the erbium-doped fiber laser (EDFL) and the first-order Brillouin laser using a 4 m high nonlinear fiber (HNLF) as Brillouin gain medium. The evolutionary power spectrum of the EDFL and the first-order Brillouin laser are investigated through adjusting the output power of tunable laser source (TLS) and 980 nm pump. The high stability of the single-and dual-wavelength operation are experimentally verified by the measured wavelength variation of ≤0.01 nm and power fluctuation of ≤1.6 dB within 100 min. With the good tunability of the TLS, the wavelength spacing of a dual-wavelength operation could be achieved in the pass band of the FBG. The fiber laser will find potential applications in fiber sensing and microwave photonics areas.

Widely Tunable Dual-Wavelength Thulium-doped fiber laser Operating in 1.8-2.0 mm Region

In this work, a tunable dual-wavelength fiber laser (DWFL) with a simple setup is proposed and demonstrated for operation in the 2.0-micron wavelength region. The proposed system employs a ring cavity with a 4-m bi-directionally pumped thulium-doped fiber (TDF) as the linear gain medium, with an inner ring cavity incorporating two tunable bandpass filters (TBPFs) used to generate the desired tunable dual-wavelength output. By fine-tuning the loss of the cavity, peaks of similar intensities for both lasing wavelengths can be obtained by overcoming suppression induced by the homogenous broadening effect, thus producing a stable dual-wavelength output. The widest channel spacing obtained is 183.6 nm, and both lasing wavelengths can be tuned across the 1.8-2.0-micron region by just adjusting the passbands of the TBPFs. The generated dual-wavelength laser has a high signal-to-noise ratio of 66 dB, and its 3-dB bandwidth is measured to be around 0.07 nm. The laser is highly stable, with little-to-none peak fluctuations and no wavelength shift in the lasing wavelengths. The proposed laser is suitable for use in multiple applications near the 2.0-micron region, such as biomedical and industrial applications due to its eye-safe properties.

Generation of Four-Wave Mixing in a Highly Non-Linear Optical Fiber Using a Tunable Dual Wavelength Fiber Laser Source

In this paper, we demonstrate a Four Wave Mixing (FWM) effect in a highly nonlinear single mode optical fiber. A tunable dual-wavelength fiber laser is used to provide the pump and signal probe to generate partially degenerate FWM. Calculations using coupled differential equations and experimental results in the generation of FWM were analyzed. We observed that FWM conversion efficiency depends more significantly on the wavelength detuning between pump and signal wavelength as compared to zero-dispersion wavelength. The tunability is achieved using an arrayed waveguide grating which provides different wavelength combinations of the dual-wavelength fiber laser output and can be tuned from 1530.47nm to 1548.61nm with a spacing of 100GHz. The highly nonlinear fiber has a nonlinear coefficient, γ of 10.8 W-1km-1. Hence, to achieve higher FWM output power the pump power of the dual wavelength fiber laser has to be higher than that of the signal probe. The optimum measured values of pump and signal power are +13.3dBm and +5dBm respectively, limited buy the current experimental setup.

Tunable Dual-Wavelength Thulium-Doped Fiber Laser Based on FBGs and a Hi-Bi FOLM

A tunable dual-wavelength thulium doped fiber laser is demonstrated experimentally. For the first time for the 2- $\mu \text{m}$ wavelength band we propose the independent tuning of the generated laser lines based on fiber Bragg gratings and the use of a Hi-Bi fiber optic loop mirror for the fine adjustment of the cavity losses to obtain stable dual-wavelength operation. Dual-wavelength laser generation with the laser lines separation in the range from 0.3 to 6.5 nm is obtained. The laser emission exhibits an optical signal-to-noise ratio better than 56 dB. Improved stability with output power fluctuations less than 1 dB is observed in dual-wavelength generation with equal power of lines.

Tunable dual-wavelength fiber laser with unique gain system based on in-fiber acousto-optic Mach-Zehnder interferometer.

A fast tunable dual-wavelength laser based on in-fiber acousto-optic Mach-Zehnder interferometer (AO-MZI) with new fabrication process is proposed. Not only could the center wavelength of the output laser be optimized with enhanced tuning range about 30 nm by tuning the polarization and the driving frequency of the radio frequency (RF) signal accordingly, but also the spectral spacing between the two output wavelengths could be tuned from ~0 nm to 2.65 nm by controlling the power of the RF signal. The tuning mechanism was also discussed.