Single-walled Carbon Nanotube Saturable Absorber Research Articles

Sub-80 fs mode-locked Tm,Ho-codoped disordered garnet crystal oscillator operating at 2081 nm.

We demonstrate a mode-locked (ML) femtosecond laser based on the disordered garnet crystal Tm,Ho:CNGG. Employing a single-walled carbon nanotube saturable absorber, pulses as short as 83 and 76fs at 2081nm are achieved without and with external compression, respectively. The latter represents, to the best of our knowledge, the shortest pulse duration obtained from any Ho-doped or Tm,Ho-codoped laser. The average power amounts to 67mW at a repetition rate of 102MHz. By analyzing the soliton ML regime, the nonlinear refractive index of Tm,Ho:CNGG is estimated to be ∼1.1×10-19 m2/W.

Generation of 84-fs pulses from a mode-locked Tm:CNNGG disordered garnet crystal laser

A mode-locked laser based on a Tm:CNNGG disordered crystal as an active medium and a single-walled carbon nanotube saturable absorber is demonstrated, operating at a central wavelength of 2018 nm. Transform-limited 84 fs pulses are generated with an average output power of 22 mW at a repetition rate of ∼90 MHz. A maximum output power of 98 mW is obtained at a slightly longer pulse duration of 114 fs.

Sub-200 femtosecond dispersion-managed soliton ytterbium-doped fiber laser based on carbon nanotubes saturable absorber.

Ultrafast fiber laser light sources attract enormous interest due to the booming applications they are enabling, including long-distance communication, optical metrology, detecting technology of infra-biophotons, and novel material processing. In this paper, we demonstrate 175 fs dispersion-managed soliton (DMS) mode-locked ytterbium-doped fiber (YDF) laser based on single-walled carbon nanotubes (SWCNTs) saturable absorber (SA). The output DMSs have been achieved with repetition rate of 21.2 MHz, center wavelength of 1025.5 nm, and a spectral width of 32.7 nm. The operation directly pulse duration of 300 fs for generated pulse is the reported shortest pulse width for broadband SA based YDF lasers. By using an external grating-based compressor, the pulse duration could be compressed down to 175 fs. To the best of our knowledge, it is the shortest pulse duration obtained directly from YDF laser based on broadband SAs. In this paper, SWCNTs-SA has been utilized as the key optical component (mode locker) and the grating pair providing negative dispersion acts as the dispersion controller.

2-GHz carbon nanotube mode-locked Yb:YAG channel waveguide laser.

We demonstrate GHz-repetition rate mode-locked operation of a femtosecond-laser-inscribed Yb:YAG channel waveguide laser using single-walled carbon nanotube saturable absorber mirror (SWCNT-SAM). A 6.3-mm-long, type II Yb:YAG waveguide laser with an extended cavity configuration delivers mode-locked picosecond (ps) pulses at GHz repetition rates. The dispersion of the laser cavity is compensated by the combination of a multi-functional output coupler and the Gires-Tournois interferometer (GTI) effect arising from an air-gap between the facet of the waveguide and the output coupler. The incident beam fluence on the SWNCNT-SAM is controlled by adjusting two intracavity lenses to avoid optical damage on the polymer nanocomposite matrix containing the SWCNTs. The average output power of our mode-locked waveguide laser is 322 mW at a pump power of 3.2 W. Nearly Fourier-limited, stable 2-ps-short pulses are generated at a repetition rate of 2.08 GHz.

Wavelength tunable L Band polarization-locked vector soliton fiber laser based on SWCNT-SA and CFBG

Wavelength tunable L-Band polarization-locked vector soliton fiber laser based on single-walled carbon nanotube saturable absorber (SWCNT-SA) and chirped fiber Bragg grating (CFBG) is presented for the first time. By inserting the SWCNT-SA into an all-fiber laser cavity, polarization-locked vector solitons (PLVS) are obtained. The CFBG glued on a plastic cantilever is used for wavelength tuning. By mechanically bending the cantilever, the center wavelength of the PLVS pulses can be continuously tuned from 1606.8 nm to 1614 nm, while the polarization-locked state is kept stable. The properties and dynamics of PLVSs are experimentally investigated and stable PLVS operation including high-order PLVSs is demonstrated. The pulse width and repetition rate are 7.06 ps and 11.9 MHz at a wavelength of 1611 nm, respectively. This work demonstrates the feasibility of using polarization-insensitive CFBG to realize wavelength tuning in PLVS fiber laser.

Dual-Comb Absolute Distance Measurement Based on a Dual-Wavelength Passively Mode-Locked Laser

A new absolute distance measurement system is demonstrated in this paper, which is based on a dual-wavelength passive mode-locked fiber laser. By controlling the intracavity loss and spectral filtering, the cavity mode-locked by a single-wall carbon nanotube saturable absorber is able to generate two pulse trains at slightly different repetition rates simultaneously with high mutual coherence. Comparisons with the commercial interferometers located on the 80-m large-scale dimensional standard show a combined measurement uncertainty of 6 $\mu$ $m+1\times {10}^{-7}L\,(k=2)$ , in an averaging time of 1 s. Our compact dual-comb system provides a low-cost way for ranging, with continuous range, rapid measurement, and high resolution.

Diode-pumped passively Q-switched Nd:YVO4 laser using a reticularly ordered single-walled carbon nanotube saturable absorber

In this letter, we demonstrate a diode-pumped passively Q-switched Nd:YVO4 laser with reticularly ordered single-walled carbon nanotube as saturable absorber. Stable Q-switched pulses with a pulse energy of 0.322μJ, a pulse width of 78.7ns and a pulse repetition rate of 410.3kHz have been obtained. Compared with the passively Q-switched laser with carbon nanotubes dispersed by sodium dodecyl sulfate (SDS), the laser with reticularly ordered single-walled carbon nanotube can produce shorter pulses and higher peak power at almost the same incident pump power. The results suggest that the reticularly ordered single-walled carbon nanotube can be an attractive candidate of saturable absorber for Q-switched laser.

Doubly Q-Switched Laser With AOM- and SWCNT-SA-Driven KTP Intracavity OPO

By simultaneously using an acousto-optic modulator (AOM) and a single-walled carbon nanotube saturable absorber, an intracavity optical parametric oscillation (IOPO) in KTiOPO 4 pumped by a dual-loss-modulated Q-switched laser has been demonstrated. With an incident pump power of 8.3 W and an AOM modulation rate of 20 kHz, the maximum output power of 375 mW for signal waves was obtained, corresponding to an optical-conversion efficiency of 4.5%. In comparison with IOPO pumped by a singly Q-switched laser with an AOM, the IOPO pumped by doubly Q-switched laser can generate signal light with shorter pulse width and higher peak power as well as better pulse stability.

High-peak-power sub-nanosecond intracavity KTiOPO4 optical parametric oscillator pumped by a dual-loss modulated laser with acousto-optic modulator and single-walled carbon nanotube

A high-peak-power low-repetition-rate sub-nanosecond intracavity KTiOPO4 (KTP) optical parametric oscillator (OPO) pumped by a doubly Q-switched and mode-locked (QML) YVO4/Nd:YVO4 laser with an acousto-optic modulator (AOM) and a single-walled carbon nanotube saturable absorber (SWCNT-SA) has been demonstrated. A maximum output power of 373 mW at a signal wavelength of 1570 nm was obtained. The smallest pulse width, highest pulse energy, and greatest peak power of mode-locking pulses were estimated to be 119 ps, 124 µJ, and 1.04 MW, respectively, under a maximum incident pump power of 8.3 W and an AOM repetition rate of 2 kHz. This OPO operation paves a simple way to produce eye-safe laser sources at 1570 nm with low repetition rates, small pulse widths, and high peak powers.

Single-walled carbon nanotube saturable absorber for a diode-pumped passively mode-locked Nd,Y:SrF2 laser

A reflective single-walled carbon nanotube as saturable absorber has been firstly adopted to a passively mode-locked Nd,Y:SrF2 crystal. Without any dispersion compensation, the stably mode-locked laser delivers pulses with pulse width as short as 1.7ps, repetition rate of 107.8MHz and center wavelength of 1056nm. The oscillator produces maximum average output power of 319mW corresponding with a high slope efficiency of 20.2%. The single pulse energy and the peak power are 2.96nJ and 1.74kW, respectively. The experimental results show that single-walled carbon nanotube is an excellent saturable absorber for mode-locked lasers.

All-Polarization Maintaining Passively Mode-Locked Fiber Laser Using Evanescent Field Interaction With Single-Walled Carbon Nanotube Saturable Absorber

We implemented a single-walled carbon nanotube (SWCNT)-based saturable absorber (SA) that evanescently interacts with light on a side-polished polarization-maintaining fiber (PMF) platform. A high-quality SWCNT/polymer composite was spin-coated onto a side-polished PMF embedded in a quartz block, where the slow optical birefringence axis of the PMF was perpendicular to the polished surface. The fabricated in-line SA had an insertion loss of -1.5 dB with a modulation depth of 0.5% for the polarization direction associated with the transvers magnetic mode. An all-PMF laser was built using the fabricated in-line SA to demonstrate self-starting, turn-key operation of Er-doped, all-fiber lasers delivering stable scalar soliton pulses. The measured 3-dB spectral bandwidth and pulse duration of the laser output were 5.1 nm and 510 fs, respectively, resulting in a time-bandwidth product of 0.320. We examined the polarization state of the soliton fiber laser output and found that the laser stably generated linearly polarized ultrashort pulses with a polarization extinction ratio of -18.4 dB.

0.8 nm single wall carbon nanotubes for wideband ultrafast pulse generation

We demonstrate wideband ultrafast optical pulse generation at 1, 1.56 and 2 μm by using single polymer composite saturable absorber (SA) based on 0.8 nm single wall carbon nanotubes (SWCNTs). The SWCNTs were mixed with sodium carboxymethylcellulose (NaCMC) to form SWCNT SA films. The film then integrated into ytterbium-(Yb-), erbium-(Er-) and thulium-(Tm-) doped ring fiber laser cavities. Using this film, we achieve 380 ps, 830 fs, and 1.24 ps mode-locked pulses at 1035, 1560, and 1933 nm, respectively. These results suggest that 0.8 nm SWCNTs are potentially useful as optical elements in wideband fiber lasers.

High-power passively mode-locked Nd:YVO(4) laser using SWCNT saturable absorber fabricated by dip coating method.

Passive mode locked laser is typically achieved by the Semiconductor Saturable absorber Mirror, SESAM, saturable absorber, which is produced by expensive and complicated metal organic chemical vapor deposition method. Carbon based single wall carbon nanotube (SWCNT), saturable absorber, is a promising material which is capable to produce stable passive mode-locking in the high power laser cavity over a wide operational wavelength range. This study has successfully demonstrated the high power mode locking laser system operating at 1 micron by using SWCNT based absorbers fabricated by dip coating method. The proposed fabrication method is practical, simple and cost effective for fabricating SWCNT saturable absorber. The demonstrated high power Nd:YVO(4) mode-locked laser operating at 1064nm have maximum output power up to 2.7W,with the 167MHz repetition rate and 3.1 ps pulse duration, respectively. The calculated output pulse energy and peak power are 16.1nJ and 5.2kW, respectively.

Mode-locked Tm,Ho:KLu(WO(4))(2) laser at 2060 nm using InGaSb-based SESAMs.

Passive mode-locking of a Tm,Ho:KLu(WO(4))(2) laser operating at 2060 nm using different designs of InGaAsSb quantum-well based semiconductor saturable absorber mirrors (SESAMs) is demonstrated. The self-starting mode-locked laser delivers pulse durations between 4 and 8 ps at a repetition rate of 93 MHz with maximum average output power of 155 mW. Mode-locking performance of a Tm,Ho:KLu(WO(4))(2) laser is compared for usage of a SESAM to a single-walled carbon nanotube saturable absorber.

Tm,Ho:KLu(WO₄)₂ laser mode-locked near 2 μm by single-walled carbon nanotubes.

We demonstrate passive mode-locking of a Tm,Ho-codoped crystalline laser operating on the Ho³⁺-ion transition ⁵I₇→⁵I₈ near 2 µm using a single-walled carbon nanotube saturable absorber. The Tm,Ho:KLu(WO₄)₂ laser emits nearly transform-limited pulses with duration of 2.8 ps at a repetition rate of 91 MHz. The output power amounts to 97 mW.

All-fiber mode-locked laser oscillator with pulse energy of 34 nJ using a single-walled carbon nanotube saturable absorber.

We demonstrate a dissipative soliton fiber laser with high pulse energy (>30 nJ) based on a single-walled carbon nanotube saturable absorber (SWCNT-SA). In-line SA that evanescently interacts with the high quality SWCNT/polymer composite film was fabricated under optimized conditions, increasing the damage threshold of the saturation fluence of the SA to 97 mJ/cm(2). An Er-doped mode-locked all-fiber laser operating at net normal intra-cavity dispersion was built including the fabricated in-line SA. The laser stably delivers linearly chirped pulses with a pulse duration of 12.7 ps, and exhibits a spectral bandwidth of 12.1 nm at the central wavelength of 1563 nm. Average power of the laser output is measured as 335 mW at an applied pump power of 1.27 W. The corresponding pulse energy is estimated to be 34 nJ at the fundamental repetition rate of 9.80 MHz; this is the highest value, to our knowledge, reported in all-fiber Er-doped mode-locked laser using an SWCNT-SA.

Integratable pulsed 2-μm laser with Tm,Mg:LiNbO3 crystal and single-walled carbon nanotube saturable absorber

Abstract We demonstrated an integratable passively Q-switched (PQS) Tm,Mg:LiNbO 3 laser with a single-walled carbon nanotube saturable absorber (SWCNT-SA) for the first time. Its laser characteristics were investigated with different output couplers. At the pump power of 9.5 W, the maximum output power of 0.93 W around 1963 nm was obtained with the output transmission of 1%. The optical conversion efficiency is 9.79%, corresponding to a slope efficiency of 17.4%. For pulsed operation, a shortest pulse width attained was 640 ns, with the pulse repetition frequency of 44.6 kHz, and the single pulse energy was 12.6 μJ.

Performance of diode-pumped Tm3+:Sc2SiO5 crystal passively Q-switched 2 μm laser

A diode-pumped passively Q-switched Tm3+:Sc2SiO5 laser with a single-walled carbon nanotube saturable absorber is demonstrated for the first time. The maximum average output power of 189mW has been achieved at 1970nm under an absorbed pump power of 4W. The minimum pulse width of 442ns was obtained at a repetition rate of 55.6kHz, corresponding to the highest peak power of 7.7W and single pulse energy of 3.4μJ, respectively.

Theoretical and experimental investigations of a nanotube-mode-locked stretched-pulse fiber laser

We report the generation of stretched pulses in a passively mode-locked fiber laser based on a single-wall carbon nanotube saturable absorber. The spectral bandwidth and pulse duration of the single stretched pulse are ∼25 nm and ∼1.43 ps, respectively. By increasing the pump power and adjusting the polarization state, bound-state stretched pulses are delivered from the fiber laser. The pulse–pulse separation and wavelength spacing of the bound-state pulses are ∼7.8 ps and ∼1 nm, respectively. Numerical simulations reproduce the experimental results and agree well with the experimental observations.

Systematical analysis of mode-locked fiber lasers using single-walled carbon nanotube saturable absorbers

The output characteristics of the Er-doped mode-locked fiber laser using a single-walled carbon nanotube saturable absorber are investigated theoretically with a nonlinear Schrödinger equation and a saturable absorption equation using realistic parameters. Stable self-starting mode-locking pulses are achieved under net normal, net zero, and net anomalous cavity group velocity dispersion (GVD) respectively. A spectrum with a flat top is obtained from the net normal cavity GVD laser while a spectrum with Kelly side-bands is obtained from the net anomalous cavity GVD laser. The characteristics of the pulse duration changing with cavity GVD and modulation depth of the single-walled carbon nanotubes are discussed. The characteristics of the mode-locking pulses from net normal, net zero, and net anomalous cavity GVD mode-locked fiber lasers are compared. These systematical results are useful for designing mode-locked fiber lasers with saturable absorbers made by different kinds of carbon nano-materials.