Tunable Q-switched Fiber Laser Research Articles

Q-switched fiber laser with tunable wavelength operation utilizing a nonlinear saturable absorption of vanadium pentoxide

Q-switched fiber laser with a tunable wavelength output is experimentally demonstrated utilizing a nonlinear saturable absorption of vanadium pentoxide (V2O5) in conjunction with a tunable bandpass filter (TBF). The V2O5 saturable absorber (SA) was prepared by mixing V2O5 with polyethylene glycol. The SA film exhibits a modulation depth of 7% with a saturation intensity of 90 MW/cm2. By integrating the SA into an erbium-doped fiber laser cavity while controlling the passband wavelength of the TBF, a Q-switched pulsed laser is realized with a tunable wavelength range of 30 nm that extends from 1535 to 1565 nm. At 1565 nm operation, the laser exhibits the highest slope efficiency of 8.31%. The repetition rate varies from 13.32 to 15.25 kHz, while the pulse width shrinks from 21.3 10 12.75 μs when the pump power rises from 14.9 to 37.7 mW. The pulse energy is 102.6 nJ at the maximum pump power of 37.7 mW. This is the first demonstration of a tunable Q-switched fiber laser operating in a 1.5 μm wavelength region utilizing V2O5 SA.

C-band tunable Q-switched fiber laser based on Alq3 as a saturable absorber

We propose a Q-switched erbium-doped fiber laser (EDFL) with a wide-tuning wavelength range by using Alq3 as a saturable absorber (SA). A tunable bandpass filter (TBF) was integrated into the cavity to produce a tunable wavelength. The wavelength was shifted continuously with ease from 1520 nm to 1563.3 nm covering almost all C-band region. The fiber laser showed a very stable performance in which the signal to noise ratio (SNR) of around 53 dB was recorded at different wavelengths. To the best of our knowledge, this work demonstrates for the first time that Alq3 has the potential to be used as an effective SA for broadband tunable Q-switched fiber lasers.

155 nm-wideband and tunable q-switched fiber laser using an MXene Ti3C2TX coated microfiber based saturable absorber

MXenes have recently gained significant research interest due to its graphene-like structure that allows for a multitude of applications such as electronics, batteries and optics to be realized. In this work, stable Q-switched pulses are passively obtained from a thulium-doped fiber laser using an MXene Ti3C2TX coated microfiber as a saturable absorber (SA). The generated pulses have center lasing wavelength 1976 nm with a pulse repetition rate and pulse width ranging between 16 kHz to 59 kHz and 13 µs to 2.4 µs respectively. The generated pulses can be tuned over a wavelength range of 155 nm from 1895 nm to 2050 nm. The MXene based SA has signficant potential for generating pulsed laser outputs that will find uses in the areas of sensing, medicine and spectroscopy around the ‘eye safe’ 2 µm region.

Tunable Q-Switched Fiber Laser Based on a Graphene Saturable Absorber Without Additional Tuning Element

A tunable passively Q-switched fiber laser is fabricated using a graphene saturable absorber. The graphene saturable absorber is composed of a tapered fiber coated with graphene nanosheets. It combines the abilities of a saturable absorber and power-dependent tunable filter, thereby simplifying the structure of the tunable passively Q-switched fiber laser. The transmission peak of the graphene saturable absorber is linearly dependent on the input power and temperature, with slopes of approximately -0.35 nm/mW and -3.63 nm/°C, respectively. The Q-switched fiber laser exhibits a tunable wavelength range of 7 nm (from 1558 to 1565 nm). The output pulse offers the shortest pulse duration of 2.22 μs with a repetition rate of 39.1 kHz and the widest pulse duration is 5.9 μs that corresponds to a repetition rate of 21.3 kHz. The maximum pulse energy is 251.9 nJ, corresponding to an average output power of 8.6 mW.

Tunable passively Q-switched ytterbium-doped fiber laser using MoWS2/rGO nanocomposite saturable absorber

• Demonstration of a tunable Q-switched ytterbium fiber laser using MoWS 2 @rGO as SA. • SA have a modulation depth of 5.91% and a low saturation intensity of 0.003 MW/cm 2 . • The generated pulse possess a tunable bandwidth of 10 nm from 1028 nm to 1038 nm. • Pulse exhibits pulse repetition rate of 90.4 kHz, a pulse width of 1.22 μs. • Pulse exhibits output power of 0.193 mW and the highest pulse energy of 2.13 Nj. We demonstrated a tunable Q-switched ytterbium-doped fiber laser (YDFL) using MoWS 2 /rGO nanocomposite as passive saturable absorber. Further, the Mo 1−x W x S 2 /rGO nanosheets, with x proportion of 0.2, are synthesized using hydrothermal exfoliation technique. The proposed nanocomposite-PVA based thin film is fabricated by mixing the MoWS 2 /rGO nanosheets with polyvinyl alcohol (PVA). The fabricated thin film is sandwiched between two fiber ferrules to realize the proposed saturable absorber (SA). Further, the proposed MoWS 2 /rGO-PVA based thin film SA exhibits a fast relaxation time and a high damage threshold which are suitable to realize a Q-switched pulsed laser with a tunable wavelength range of 10 nm that extends from 1028 nm to 1038 nm. For the highest pump power of 267.4 mW, the generated Q-switched pulses exhibit a narrow pulse width of 1.22 μs, the pulse repetition rate of 90.4 kHz, the highest pulse energy of 2.13 nJ and its corresponding average power of 0.193 mW. To the best of author’s knowledge, this is the first realization of a tunable Q-switching fiber laser in a 1 μm wavelength using MoWS 2 /rGO nanocomposite saturable absorber.

Tunable High-Power Q-Switched Fiber Laser Based on BP-PVA Saturable Absorber

Black phosphors (BP) nano-materials have been extensively investigated in the past years. However, the character of easily oxidizable limits BP's stability. Here a long-term-stable tunable Q-switched fiber laser with BP polymer composite (polyvinyl alcohol, PVA) as saturable absorber is realized. The modulation depth and the saturation power intensity of the BP-PVA film are 8.3% and 7.9 MW/cm2, respectively. A high average output power of 12.03 mW is obtained under the pump power of 400 mW. The shortest pulse width and maximum single pulse energy are 1.365 μs and 148.63 nJ, respectively. Meanwhile, the output spectra have a 2.5-nm blue shift when the pump power increases. The results prove that as a Q-switcher, BP polymer composite has a good performance on high power and excellent stability pulsed laser.

Effects of wavelength filtering on pulse dynamics in a tunable, actively Q-switched fiber laser

We present a numerical simulation, validated by experimental analysis, of the effect of wavelength filtering on pulse dynamics of a wavelength-tunable Erbium-doped fiber Q-switched laser in a ring configuration. Travelling wave time-dependent model is implemented using finite difference time domain (FDTD) method to accurately simulate the population dynamics and the pulse evolution in the ring laser. Such a model is experimentally validated for a wavelength tunable Q-switched fiber laser and stable Q-switched pulses are obtained over a wavelength tuning range of ∼30nm in the C-band.

基于碲化铋纳米片的全光可控调Q光纤激光器

基于碲化铋纳米片的全光可控调Q光纤激光器

Ag-nanoparticle as a Q switched device for tunable C-band fiber laser

The use of silver (Ag)-nanoparticle as saturable absorber (SA) to induce tunable Q-switched fiber laser in C-band is demonstrated. The Ag-nanoparticle SA exhibits modulation depth of 31.6% and saturation intensity of 0.54MWcm−2. The SA is integrated into the laser cavity by sandwiching it between two fiber ferrules. Lasing in CW region starts at 10mW, whereas stable self-starting Q-switching with a central wavelength of 1558.4nm begins at 20mW. As the pump power increases, the repetition rate varies from 10.5kHz to 24.4kHz and the narrowest pulse width obtained is around 6.5µs. The Q-switched laser has a tuning range of 27.3nm (1552.9–1580.2nm). The stability of the pulse is verified from the radio-freqeuncy (RF) spectrum with a measured signal-to-noise ratio (SNR) of 46.22dB. The ability of Ag-nanoparticle as an effective SA may lead to further development of pulsed fiber laser in the field of photonics.

Tunable Q-switched fiber laser using zinc oxide nanoparticles as a saturable absorber.

Nanomaterials have ignited new interest due to their distinctive electronic, mechanical, and optical properties. Zinc oxide nanostructures are fabricated into thin film and then inserted between two fiber ferrules to act as a saturable absorber (SA). The modulation depth and insertion loss of the SA are 5% and 3.5 dB, respectively. When the ZnO-SA is incorporated into the laser cavity, a stable Q-switched pulse tunable from 1536 to 1586 nm (50 nm range) with pulse energy up to 46 nJ was observed. Our result suggests that ZnO is a promising broadband SA to generate passively Q-switched fiber lasers.

Tunable Q-switched fiber laser based on saturable edge-state absorption in few-layer molybdenum disulfide (MoS₂).

We fabricate a few-layer molybdenum disulfide (MoS₂) polymer composite saturable absorber by liquid-phase exfoliation, and use this to passively Q-switch an ytterbium-doped fiber laser, tunable from 1030 to 1070 nm. Self-starting Q-switching generates 2.88 μs pulses at 74 kHz repetition rate, with over 100 nJ pulse energy. We propose a mechanism, based on edge states within the bandgap, responsible for the wideband nonlinear optical absorption exhibited by our few-layer MoS₂ sample, despite operating at photon energies lower than the material bandgap.

Wideband tunable Q-switched fiber laser using graphene as a saturable absorber

An ultra-wide wavelength tuning range, which covers three different band regions consisting of the S-, C-, and L-bands, is proposed and demonstrated for a graphene-based Q-switched erbium-doped fiber laser using a tunable bandpass filter as the wavelength tuning and filtering mechanism. A 3 m length of erbium-doped fiber is used as the gain medium in a ring laser cavity configuration, with absorption coefficients of between 11 and 13 dB m−1 at 980 nm and about 18 dB m−1 at 1550 nm. The tuning range of the Q-switching pulses covers a wide wavelength range of 58 nm, which spans from 1512.5 nm to 1570.5 nm. In addition, the lasing and Q-switching thresholds are considerably low, with respective values of ∼11.0 mW and ∼18.4 mW. A repetition rate of 55.3 kHz is obtained at the maximum pump power of 100.4 mW, together with pulse width and pulse energy of 1.6 μs and 25.8 nJ, respectively.

A wavelength tunable Q-switched fiber laser using fiber Bragg gratings

This paper reports on a Q-switched Er-doped fiber laser using the stress dependence of a wavelength of reflected light from fiber Bragg gratings. The laser cavity consists of a 0.5-m-long Er-doped fiber and two fiber gratings (FG) attached at both ends of the fiber. The pump laser is a 1.48 μm semiconductor laser. Wavelength control of the reflected light from the FG was carried out by bending a metal rod to which the FGs were attached, or by applying stress to the FG using a piezoelectric transducer (PZT). Q-switching was carried out by changing the wavelength of the reflected light at high speed using the PZT. When the pump power was 26 mW and the repetition rate was 1 kHz, the optical pulse had a pulse width of 2.46 μs and a peak power of 2.1 mW. By adjusting the reflection from the FG, the oscillation wavelength was varied by 4 nm. The relationship among the reflection spectrum of the FG, the wavelength shift of the reflected light from the FG, the pump power, and the pulse width of the optical pulse was clarified. © 1998 Scripta Technica. Electron Comm Jpn Pt 2, 80(11): 12–21, 1997