Holmium-doped Fiber Laser Research Articles

1.35 μJ, 5.33 W Noise-Like Pulse Emission From an All-Polarization Maintaining Holmium-Doped Fiber Laser System

1.35 μJ, 5.33 W Noise-Like Pulse Emission From an All-Polarization Maintaining Holmium-Doped Fiber Laser System

High Output Power Holmium-Doped Fiber Laser at 2100 nm

A theoretical model of three levels describing Holmium-doped fiber lasers pumped by Laser-diodes 1150nm is present. Based on the model, efficiency as well as output power depend on the length of active media, are investigate, using the MATLAB program (R 2019 a). The results shows that output power and efficiency of optical fibers are exponential inverse relationship with increment fiber length, for 1m output power have highest value 100.4W, while efficiency have 44.6% at 0.05m.

High Output Power Holmium-Doped Fiber Laser at 2100 nm

A theoretical model of three levels describing Holmium-doped fiber lasers pumped by Laser-diodes 1150nm is present. Based on the model, efficiency as well as output power depend on the length of active media, are investigate, using the MATLAB program (R 2019 a). The results shows that output power and efficiency of optical fibers are exponential inverse relationship with increment fiber length, for 1m output power have highest value 100.4W, while efficiency have 44.6% at 0.05m.

Tunable mode-locked holmium-doped fiber laser based on GIMF-SIMF-GIMF structure at 2.09 µm

In this study, a structure of graded-index multimode fiber-step index multimode fiber-graded index multimode fiber (GIMF-SIMF-GIMF) was used as a saturable absorber (SA) to generate mode-locking in a holmium-doped fiber laser (HDFL). The HDFL was pumped with a compact in-house thulium-doped fiber laser (TDFL) operating at 1943 nm with a maximum output power of 2.1 W. Mode-locked pulses with a pulse duration of 1.61 ps were successfully generated at the center wavelength of 2091.1 nm. The pulse had a repetition rate of 12.79 MHz with a bit of fluctuation of 2.09 %, indicating stable pulses. The mode-locked pulses were also tunable with a range from 2086.5 nm to 2091.1 nm by stretching the GIMF part of the SA. This first report demonstrated mode-locking using nonlinear multimode interference (NL-MMI) using GIMF-SIMF-GIMF structure as a saturable absorber in HDFL operating near 2.1 µm wavelength.

Dual-comb operation in an all-polarization-maintaining ultrafast holmium-doped fiber laser

We present a dual-comb fiber laser in the wavelength range of 2.1 μm from an all-polarization-maintaining holmium-doped fiber laser based on a reflective nonlinear amplifying loop mirror (Figure- 9) scheme. The dynamics of the laser, where net cavity dispersion is controlled by varying the length of the intra-cavity dispersion-compensating fiber (DCF), has been fully investigated. The laser is found capable of mode-locking with a net cavity dispersion value ranging from net anomalous (−0.19 ps2) to net normal (0.11 ps2). More interestingly, without any intentional design, dual-comb operation with a relatively small offset frequency, down to a few Hertz, is observed in the system. The dual-comb operation is believed to arise from direction multiplexing in the loop cavity and polarization multiplexing in the linear arm, and is likely to be a generic solution for Figure- 9 lasers. Such a dual-comb system with a characteristic small frequency difference can provide sample interval with higher precision in asynchronous optical sampling (ASOP) applications.

Mode-locking in holmium doped fiber laser operating at 2.06 µm using manganese violet

Mode-locking in holmium doped fiber laser operating at 2.06 µm using manganese violet

1.7 W holmium-doped fluoroindate fiber laser at 3920 nm.

A monolithic fiber laser emitting 1.7 W at 3920 nm is experimentally demonstrated in a Ho3+:InF3 fiber. The cavity comprises a pair of highly reflective fiber Bragg gratings written in the active fiber with the femtosecond phase-mask scanning technique and is spliced to the pump diode with a robust silica-to-fluoride fiber splice. This work is an important step toward high-power all-fiber laser operating in the vicinity of 4 µm.

Pair induced quenching in high concentration Holmium-doped fiber amplifiers

The spectrum required for future optical communication systems is being extended towards the C-, L- and U-bands, resulting in a significant interest in the spectral region around 2 μm wavelength. Since Holmium doped fiber amplifiers (HDFAs) provide amplification in this spectral region, they have become a focus of researchers working on doped fiber amplifiers. A major factor resulting in the performance degradation of HDFAs is the inhomogeneous energy transfer within Ho3+ ion-pairs in high-concentration Holmium-doped fibers (HDFs), an effect generally known as pair-induced quenching (PIQ). In this paper, we study the luminal and temporal dynamics of pulses of different repetition rates at 2.05 μm in high-concentration HDFs considering the effects of ion-pairs. Input pulses having repetition rates of 25 GHz and 500 kHz are generated using wavelength tunable actively mode-locked Holmium-doped fiber laser (AML-HDFL) based on a single ring cavity and bidirectional pumping. The characteristics of the pulses propagating through high-concentration HDF are analyzed based on different metrics such as average power, peak power, pulse energy, full-width at half maximum (FWHM), and time delay without and with ion-pairs for values of fraction of ion-pairs k = 0 and k = 10%, respectively. The results obtained at optimized length of HDF show that ion-pairs significantly degrade the average power, peak power, and energy of the output pulses for both of the repetition rates. For both k = 0 and k = 10%, the FWHM and shape of the output pulses remain same in the presence of the ion-pairs while, time delay of 4 ps and 19 ns is observed in the output pulses at repetition rates of 25 GHz and 500 kHz, respectively. The effects of increasing the pump and signal power on the average power and energy of the output pulses for k = 0 and k = 10% are also discussed for both repetition rates. This analysis provides important guidelines for designers of 2 μm fiber lasers and amplifiers based on high-concentration HDFs.

Brief Review of Recent Developments in Fiber Lasers

This review covers the recent achievements in high-power rare earth (RE)-doped fiber lasers, Raman fiber lasers, and Brillouin fiber lasers. RE-doped fiber lasers have many applications such as laser cutting, laser welding, laser cleaning, and laser precision processing. They operate in several wavelength ranges including 1050–1120 nm (ytterbium-doped fiber lasers), 1530–1590 nm (erbium- and erbium–ytterbium-doped fiber lasers), and 1900–2100 nm (thulium- and holmium-doped fiber lasers). White spaces in the wavelength spectrum, where no RE-doped fiber lasers are available, can be covered by Raman lasers. The heat power generated inside the laser active medium due to the quantum defect degrades the performance of the laser causing, for example, transverse-mode instability and thermal lensing. It can even cause catastrophic fiber damage. Different approaches permitting the mitigation of the heat generation process are considered in this review. Brillouin fiber lasers, especially multiwavelength Brillouin fiber lasers, have several important applications including optical communication, microwave generation, and temperature sensing. Recent progress in Brillouin fiber lasers is considered in this review.

Mode-Locking and Q-switching in Holmium Doped Fiber Laser Using Topological Insulator (Sb2Te3) as Saturable Absorber

Mode-Locking and Q-switching in Holmium Doped Fiber Laser Using Topological Insulator (Sb₂Te₃) as Saturable Absorber

Pedestal-cladding-pumped holmium fiber laser optimization using an analytical model

An analytical model of holmium-doped fiber laser is used to calculate optimal fiber length, pump wavelength and signal wavelength under in-band pumping conditions while considering fiber losses. The calculations show the advantages of a new type of pedestal-cladding-pumped fiber.

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.

A high power and repetition rate wavelength tunable actively mode-locked Holmium-doped fiber laser for bidirectional transmission between two HAPS

A high power and repetition rate wavelength tunable actively mode-locked Holmium-doped fiber laser for bidirectional transmission between two HAPS

Theoretical Study for Holmium Doped Fiber Laser

Rate equation approach has been prepared for interaction process in optical fiber laser of three levels system. Information that we have dealt with conclude the results theoretically processed using the MATLAB program (R 2019 a). The results show that concentration of rare earth ions and the efficiency of optical fibers is an inverse relationship. At concentration 1×1023 ion m-3, the lowest & highest value of output power & laser efficiency 19.2W & 44.6% respectively. While at concentration 10×1023 ion m-3, the highest & lowest value of output power & laser efficiency 83.2W & 19.6% respectively.

Dumbbell-Shaped Ho-Doped Fiber Laser Mode-Locked by Polymer-Free Single-Walled Carbon Nanotubes Saturable Absorber.

We propose a simple dumbbell-shaped scheme of a Holmium-doped fiber laser incorporating a minimum number of optical elements. Mode-locking regimes were realized with the help of polymer-free single-walled carbon nanotubes (SWCNTs) synthesized using an aerosol (floating catalyst) CVD method. We show that such a laser scheme is structurally simple and more efficient than a conventional one using a ring cavity and a similar set of optical elements. In addition, we investigated the effect of SWCNT film transmittance, defined by the number of 40 nm SWCNT layers on the laser's performance: operating regimes, stability, and self-starting. We found that three SWCNT layers with an initial transmittance of about 40% allow stable self-starting soliton mode-locking at a wavelength of 2076 nm with a single pulse energy of 0.6 nJ and a signal-to-noise ratio of more than 60 dB to be achieved.

Continuous-wave single-frequency holmium-doped fiber laser based on saturable absorber

The single-frequency holmium-doped fiber laser with spectral filtration based on a dynamics filter formed in heavily holmium-doped fiber is presented. The continuous wave lasing on a single longitudinal mode in the spectral region of 2.1 μm with an output power of 1.6 mW is shown when the filtering fiber is cooled with liquid nitrogen. The optical signal-to-noise ratio and the relative intensity noise were more than 30 dB and — 62.8 dB Hz−1, respectively. The developed source can be used for gas spectroscopy as well as for remote atmosphere sensing of such gases as carbon dioxide, nitric oxide, ammonia, carbon monoxide and others.

Wavelength tunable dissipative soliton resonant holmium-doped fiber laser beyond [formula omitted

We propose a wavelength tunable dissipative soliton resonant (DSR) mode-locked holmium-doped fiber laser operating at wavelength exceeding 2.1μm. Mode-locking is realized by employing nonlinear amplifying loop mirror technique. Using a piece of long gain fiber to offer enough gain above 2.1μm. A section of ultra-high numerical aperture fiber (UHNAF) with normal dispersion and high nonlinearity is used to reduce mode-locking threshold and increase the intracavity nonlinearity. At the optimized gain fiber length of 9.8 m and UHNAF length of 55 m, 2109 nm DSR pulse with 3-dB spectrum width of 0.46 nm is obtained. Thanks to the birefringence-induced spectral filter effect, the central wavelength of DSR can be tuned from 2102.7 to 2120.5 nm with wavelength range of 17.8 nm.

Multiple soliton mode-locking operations of a Holmium-doped fiber laser based on nonlinear polarization rotation

Multiple soliton mode-locking operations are realized in a Holmium-doped (Ho-doped) fiber laser based on nonlinear polarization rotation (NPR) technique. The fundamental mode-locking (FML) operation with a repetition rate of 19.91 MHz and a pulse duration of 974 fs is realized at 2056.1 nm. Bunched solitons operation with up to 7 soliton pulses is firstly implemented in the Ho-doped fiber laser by increasing the pump power. The Ho-doped fiber laser can also evolve into the harmonic mode-locking (HML) operation at ∼ 2056 nm by finely adjusting the intra-cavity parameters. The pulse duration is 965 fs at the highest repetition rate of 139.19 MHz, which is believed to be the first report on the femtosecond HML operation in the Ho-doped fiber lasers.

Numerical analysis of hybrid mode-locking stability in a Ho-doped fiber laser.

We numerically study a hybrid mode-locked holmium-doped fiber laser based on the coupled nonlinear Schrödinger equations, by introducing nonlinear polarization rotation and saturable absorber in a same cavity. Maps of mode-locking states related to the intracavity wave-plates are created to evaluate the stability of mode-locking. Nonlinear polarization rotation imposes negative effect of linear absorption and even reverse saturable absorption to the pulses in the hybrid cavity. Saturable absorber compensates the negative effect from nonlinear polarization rotation, then consequently contributes to the stability of single-pulse mode-locking states. The extension of pulse time duration indicates the dynamic synergy between nonlinear polarization rotation and saturable absorber rather than the static combination mechanism of them.

2.1 m, high-energy dissipative soliton resonance from a holmium-doped fiber laser system

Abstract We propose a 2.1 μm high-energy dissipative soliton resonant (DSR) fiber laser system based on a mode-locked seed laser and dual-stage amplifiers. In the seed laser, the nonlinear amplifying loop mirror technique is employed to realize mode-locking. The utilization of an in-band pump scheme and long gain fiber enables effectively exciting 2.1 μm pulses. A section of ultra-high numerical aperture fiber (UHNAF) with normal dispersion and high nonlinearity and an output coupler with a large coupling ratio are used to achieve a high-energy DSR system. By optimizing the UHNAF length to 55 m, a 2103.7 nm, 88.1 nJ DSR laser with a 3-dB spectral bandwidth of 0.48 nm and a pulse width of 17.1 ns is obtained under a proper intracavity polarization state and pump power. The output power and conversion efficiency are 0.233 W and 4.57%, respectively, both an order of magnitude higher than those of previously reported holmium-doped DSR seed lasers. Thanks to the high output power and nanosecond pulse width of the seed laser, the average power of the DSR laser is linearly scaled up to 50.4 W via a dual-stage master oscillator power amplifier system. The 3-dB spectral bandwidth broadens slightly to 0.52 nm, and no distortion occurs in the amplified pulse waveform. The corresponding pulse energy reaches 19.1 μJ, which is the highest pulse energy in a holmium-doped mode-locked fiber laser system to the best of our knowledge. Such a 2.1 μm, high-energy DSR laser with relatively wide pulse width has prospective applications in mid-infrared nonlinear frequency conversion.