Thulium-doped Fiber Ring Laser Research Articles

Watt-level 1.7-μm single-frequency thulium-doped fiber oscillator

Here we demonstrated an efficient high-power single-frequency thulium-doped fiber ring laser operating at 1720 nm. Three cascaded sub-rings were inserted into the main cavity to significantly enlarge the effective free spectral range. By incorporating a fiber Bragg grating, the single longitudinal mode operation was achieved. The maximum single-frequency output power reached up to 1.11 W under 3.75-W launched pump power, while the slope efficiency with respect to the absorbed pump power was 46.4%. The laser linewidth at maximum single-frequency power was measured of 1.9 kHz. Potential power scaling of the single-frequency output power with different quantity and lengths of the sub-rings was also theoretically investigated.

Generation and dynamics of stepped h-shaped noise-like pulses in a mode-locked thulium-doped fiber ring laser

New h-shaped pulses with stepped flattops are observed in a mode-locked thulium-doped fiber laser (251 m long cavity) by the nonlinear polarization rotation technique. The step at the end of an h-shaped pulse has a lower intensity and an almost fixed duration (~5 ns) when it is tuned in the range of several tens of ns. By incorporating simple gain dynamics and a model of saturable absorption, the h-shaped pulses are simulated from a retrieval of noise-like pulse solutions. The change regularity of pulses in experiment is basically verified and explained by the numerical results. An analysis reveals that gain depletion and mode-locking threshold are key factors to form the ‘h’ shape. It is also proposed that the step tail is a kind of noise-like square wave pulse generated at the trailing edge.

Self-wavelength-sweeping in a bi-directional thulium-doped fiber ring laser

We report for the first time the self-wavelength-sweeping phenomenon of a bi-directional thulium-doped fiber ring laser. The laser wavelength can spontaneously sweep in both lasing directions at a rate up to 0.2 nm s−1 over 15 nm sweeping range in the 1.95 μm wavelength region. The sweeping rate can be controlled by simply changing the state of polarization of the laser cavity. The laser can be tuned to generate a periodical wavelength-swept output with microsecond pulses in the time domain. The sweep rate can also be tuned to zero to give a static lasing wavelength.

Bi-Directional Mode-Locked Thulium Fiber Laser as a Single-Cavity Dual-Comb Source

We demonstrate the use of a bi-directional mode-locked thulium doped fiber ring laser as a single cavity free-running dual-comb source. We consider the effect of group-velocity dispersion on the repetition rate difference between the two combs and demonstrate a tunable repetition rate difference from 48–229 Hz. Dual-comb spectroscopy of atmospheric H2O near $1.87~\mu \text{m}$ is performed over a 1.47-m air path in laboratory with a peak single-shot signal-to-noise ratio of 27.5.

Low repetition rate passively mode-locked thulium-doped fiber laser for LIDAR system

An all-fiber passively mode-locked thulium-doped fiber (TDF) ring laser with a repetition rate of 736 kHz was demonstrated. This is the lowest repetition rate among those of mode-locked TDF lasers to the best of our knowledge. Numerical calculations to find the best solution for successful mode-locking in a highly lossy oscillator were made based on Haus’s master equation with variables such as oscillator loss, small signal gain and modulation depth. Based on the calculation, the laser was configured, where nonlinear polarization rotation (NPR) and two stages of TDF amplifier were properly applied. The overall length of oscillator is about 290 m. The output optical spectrum has a FWHM of 28 nm at 2 μm.

Mode-Locked Thulium-Doped Fiber Laser Using a Single-Layer-Graphene-Covered Tapered Fiber

For the first time, to the best of our knowledge, we demonstrate an all-fiber passively mode-locked thulium-doped fiber ring laser using evanescent field coupling in a tapered fiber with a single-layer graphene as a saturable absorber. The modulation depth limitation of a single-layer graphene is overcome by incorporating the graphene layer along the fiber longitudinal plane, effectively extending the interaction length between the single-layer graphene and the evanescent field. The fiber oscillator produces stable 0.98 ps soliton pulses with a pulse energy of 544 pJ, a 3 dB spectral bandwidth of 4.6 nm, and an RF signal-to-noise ratio of 70 dB.

Widely Tunable Watt-Level Single-Frequency Tm-Doped Fiber Ring Laser as Pump for Mid-IR Frequency Generation

We demonstrate a thulium-doped fiber ring laser (TDFRL) integrated with an amplifier, which has a watt-level single-frequency output at 2 $\mu\text{m}$ with a 120-nm wavelength tunability. The TDFRL is constructed based on a hybrid ring-linear resonator configuration. An unpumped TDF is incorporated as a self-constructed saturable absorption grating. A blazed grating aligned in a Littrow configuration is employed for broadband wavelength-selective feedback. The characteristics of the laser output mode are analyzed by using an all-fiber scanning ring resonator.

Graphene-based, ultrafast Er-doped fiber laser with linearly polarized output pulses

We demonstrate an all-fiber, Er-doped fiber laser mode-locked with a graphene-based saturable absorber. The resonator is designed using only polarization maintaining fibers and components, which allows to achieve linearly polarized output beam. The laser delivers 595 fs long pulses at 1560 nm center wavelength with 6.3 nm bandwidth and 67 MHz repetition rate. As a saturable absorber, a graphene-polymer composite was used. Full Text: PDF References Q. L. Bao, H. Zhang, Y. Wang, Z. H. Ni, Z. X. Shen, K. P. Loh, D. Y. Tang, "Atomic-Layer Graphene as a Saturable Absorber for Ultrafast Pulsed Lasers", Adv. Funct. Mater. 19, 3077 (2009). CrossRef T. Hasan, Z. Sun, F. Wang, F. Bonaccorso, P. H. Tan, A. G. Rozhin, A.C. Ferrari, "Nanotube?Polymer Composites for Ultrafast Photonics", Adv. Mater. 21, 3874 (2009). CrossRef H. Zhang, D. Y. Tang, L. M. Zhao, Q. L. Bao, and K. P. Loh, "Large energy mode locking of an erbium-doped fiber laser with atomic layer graphene", Opt. Express 17, 17630 (2009). CrossRef Z. Sun, T. Hasan, F. Torrisi, D. Popa, G. Privitera, F. Wang, F. Bonaccorso, D. M. Basko, A. C. Ferrari, "Graphene Mode-Locked Ultrafast Laser", ACS Nano 4, 803 (2010). CrossRef Z. Sun, D. Popa, T. Hasan, F. Torrisi, F. Wang, E. JR Kelleher, J. C Travers, V. Nicolosi, A. C Ferrari, "A stable, wideband tunable, near transform-limited, graphene-mode-locked, ultrafast laser", Nano Res. 3, 653 (2010). CrossRef D. Popa, Z. Sun, F. Torrisi, T. Hasan, F. Wang, and A. C. Ferrari, "Sub 200 fs pulse generation from a graphene mode-locked fiber laser", Appl. Phys. Lett. 97, 203106 (2010). CrossRef H. Zhang, D. Y. Tang, L. M. Zhao, Q. L. Bao, K. P. Loh, B. Lin, and S. C. Tjin, "Compact graphene mode-locked wavelength-tunable erbium-doped fiber lasers: from all anomalous dispersion to all normal dispersion", Laser Phys. Lett. 7, 591 (2010). CrossRef H. Zhang, Q. Bao, D. Tang, L. Zhao, and K. Loh, "Large energy soliton erbium-doped fiber laser with a graphene-polymer composite mode locker", Appl. Phys. Lett. 95, 141103 (2009). CrossRef J. Xu, S. Wu, H. Li, J. Liu, R. Sun, F. Tan, Q.-H. Yang, P. Wang, "Dissipative soliton generation from a graphene oxide mode-locked Er-doped fiber laser", Opt. Express 20, 23653 (2012). CrossRef P.L. Huang, S. Lin, C. Yeh, H. Kuo, S. Huang, G. Lin, L. Li, C. Su, W. Cheng, "Stable mode-locked fiber laser based on CVD fabricated graphene saturable absorber", Opt. Express 20, 2460 (2012) CrossRef X.H. Li, Y.G. Wang, Y.S. Wang, Y.Z. Zhang, K. Wu, P.P. Shum, X. Yu, Y. Zhang, Q.J. Wang, "All-normal-dispersion passively mode-locked Yb-doped fiber ring laser based on a graphene oxide saturable absorber", Laser Phys Lett. 10, 075108 (2013). CrossRef M. Zhang, E. J. R. Kelleher, F. Torrisi, Z. Sun, T. Hasan, D. Popa, F. Wang, A. C. Ferrari, S. V. Popov, and J. R. Taylor, "Tm-doped fiber laser mode-locked by graphene-polymer composite" Opt. Express 20, 25077 (2012). CrossRef Q. Wang, T. Chen, B. Zhang, M. Li, Y. Lu, and K. P. Chen, "All-fiber passively mode-locked thulium-doped fiber ring laser using optically deposited graphene saturable absorbers", Appl. Phys. Lett. 102, 131117 (2013). CrossRef G. Sobon, J. Sotor, I. Pasternak, A. Krajewska, W. Strupinski, K. M. Abramski, "Thulium-doped all-fiber laser mode-locked by CVD-graphene/PMMA saturable absorber", Opt. Express 21, 12797 (2013). CrossRef G. Sobon, J. Sotor, I. Pasternak, K. Grodecki, P. Paletko, W. Strupinski, Z. Jankiewicz, K.M. Abramski, "Er-Doped Fiber Laser Mode-Locked by CVD-Graphene Saturable Absorber", J. Lightwave Technol. 30, 2770 (2012). CrossRef A. Martinez, K. Fuse, B. Xu, and S. Yamashita, "Optical deposition of graphene and carbon nanotubes in a fiber ferrule for passive mode-locked lasing", Opt. Express 18, 23054 (2010). CrossRef Y. M. Chang, H. Kim, J. H. Lee, and Y. Song, "Multilayered graphene efficiently formed by mechanical exfoliation for nonlinear saturable absorbers in fiber mode-locked lasers", Appl. Phys. Lett. 97, 211102 (2010). CrossRef A. Martinez, K. Fuse, and S. Yamashita, "Mechanical exfoliation of graphene for the passive mode-locking of fiber lasers", Appl. Phys. Lett. 99, 121107 (2011). CrossRef G. Sobon, J. Sotor, K. M. Abramski, "All-polarization maintaining femtosecond Er-doped fiber laser mode-locked by graphene saturable absorber", Laser Phys. Lett. 9, 581 (2012). CrossRef J. Sotor, G. Sobon, K. M. Abramski, "Scalar soliton generation in all-polarization-maintaining, graphene mode-locked fiber laser", Opt. Lett. 37, 2166 (2012). CrossRef M. L. Dennis, I. N. Duling III, "Experimental study of sideband generation in femtosecond fiber lasers", IEEE J. Quantum Electron. 30, 1469 (1994) CrossRef

All-fiber ultrafast thulium-doped fiber ring laser with dissipative soliton and noise-like output in normal dispersion by single-wall carbon nanotubes

An ultrafast thulium-doped fiber laser with large net normal dispersion has been developed to produce dissipative soliton and noise-like outputs at 1.9 μm. The mode-locked operation was enabled by using single-wall carbon nanotubes as saturable absorber for all-fiber configuration. Dissipative soliton in normal dispersion produced by the fiber laser oscillator was centered at 1947 nm with 4.1-nm FWHM bandwidth and 0.45 nJ/pulse. The output dissipative soliton pulses were compressed to 2.3 ps outside the laser cavity.

Characteristics of dissipative solitons in an all-fiber thulium-doped fiber ring laser

We numerically investigate the output characteristics of dissipative solitons (DSs) in a thulium-doped fiber ring laser mode-locked by a semiconductor saturable absorber mirror (SESAM). It is shown that DSs could be formed with the SESAM acting as a mode-locker and a filtering-equivalent component. The pump power, together with the net-cavity dispersion, determines the properties of the generated DSs. The numerical results qualitatively match with previously reported experimental observations. The pulse compression of the generated DSs is numerically demonstrated by using a segment of single-mode fiber with anomalous dispersion as an external pulse compressor. The corresponding compressed pulses have a minimum duration of 450 fs.

All-fiber passively mode-locked thulium-doped fiber ring laser using optically deposited graphene saturable absorbers

An all-fiber passively mode-locked thulium-doped fiber ring oscillator is constructed using optically deposited few layer graphene micro-sheets as the saturable absorber (SA). The mode-lock operation was achieved by 130-mW pump power at 1.5-μm. The fiber oscillator produces 2.1-ps soliton pulse output with 80-pJ per pulse energy. The 3-dB bandwidth of the laser output was measured as 2.2-nm. The RF signal-to-noise ratio of 50-dB and sub 20-Hz 3-dB bandwidth of the laser output confirms the stable laser operation with low time jittering. This paper shows that graphene can be an effective saturable absorber for the development of mid-IR fiber mode-locked laser.

All-fiber widely wavelength-tunable thulium-doped fiber ring laser incorporating a Fabry-Perot filter

We demonstrate 1940 to 2010 nm continuous CW wavelength-tuning in a thulium-doped fiber laser (TDFL), using only fiber-format components. A fiber Fabry-Perot (FP) tunable filter is employed to achieve the wavelength tunability of 70 nm. By imposing a 200 Hz triangle wave signal on the filter, rapid wavelength-sweeping is demonstrated from 1952 to 1992 nm every 5 ms, corresponding to 8 nm/ms. This all-fiber wavelength-tunable and swept laser may find applications such as gas monitoring in the wavelength region of 2 μm.

Tunable thulium-doped all-fiber laser

We demonstrate a tunable thulium-doped fiber ring laser wherein a single fused coupler acts simultaneously as the wavelength-division multiplexing for pump radiation, a lasing wavelength selective element, and output mirror. Temperature tuning of up to 2 nm//spl deg/C over a range of 40 nm and polarization tuning of over 100 nm within the spectral range from 1810 to 1930 nm have been obtained.

Broadly tunable sub-500 fs pulses from an additive-pulse mode-locked thulium-doped fiber ring laser

We report an additive-pulse mode-locked (APM) thulium-doped fiber ring laser producing 350–500 fs pulses tunable from 1798 to 1902 nm. The laser operates in the soliton regime, where periodic perturbations cause predictable sidebands and modulation in the optical spectrum.