Q-Switched Ultrafast TDFL Using MWCNTs-SA at 2 µm Region

Abstract

Abstract-We demonstrate an ultrafast TDFL Q-switched pulse in 2 µm wavelength using multi-walled carbon nanotubes (MWCNTs) as passive saturable absorber (SA). MWCNTs film is sandwiched between two fibre connectors or patch cords after deposited with index matching gel on the fibre ferrules. Thulium-doped fibre was pumped using 1552 nm source in the ring cavity. The repetition rate for the pulses can be tuned from 13.33 kHz to 21.07 kHz by varying the pump power from 307.5 mW to 371.4 mW. At the maximum power, the pulse generated energy of 87.34 nJ with full-width at half maximum (FHWM) of 8.21 µs.Index Terms-Multi-walled carbon nanotubes, passive saturabe absorber, Q-switching.

Tunable passively Q-switched thulium-doped fiber laser operating at 1.9 μm using arrayed waveguide grating (AWG)

“…In contrast with an earlier demonstration by H. Ahmad et al and M. T. Ahmad et al [37,38], the demonstration of the passively Q-switched output using graphene and MWCNT at operating wavelength of 2.0 mm has a lower maximum repetition rate of around 16.0 kHz and 21.0 kHz respectively compared to our experiment which has a maximum value of 68.3 kHz at 1871.6 nm. Moreover, all the tuned wavelengths in this demonstration have also higher maximum repetition rates compared to the mentioned works, which is about an average of 60 kHz.…”

Dual-wavelength passively Q-switched Erbium-doped fiber laser with MWCNTs slurry as saturable absorber

“…Figure 6 illustrates the repetition and pulse width versus the input pump power. By increasing the input pump power from 26mW to 74mW, the pulse train repetition rate increases from 25kHz to 78kHz, while the pulse width is narrowed from 17.84s to 5.24μs, making the obtained shortest pulse width better than the reported works in [8,11,15]. Figure 7 shows instantaneous peak power and pulse energy versus pump power.…”

“…They possess a sturdy mechanical strength, as well as higher thermal stability and damage threshold as compared to SWCNTs. Having multiple walls has made them capable of absorbing more photons energy per nanotubes [8].The generation of a dual wavelength Q-switched fiber laser is crucial as it brings about many advantages over single wavelength generation particularly as a medium in various applications such as supercontinuum generation, terahertz generation and nonlinear optics [9][10]. In a fiber laser, the generation of a passively dual wavelength laser was demonstrated by using a various range of materials as a saturable absorber, including selenium bismuth (Bi 2 Se 3 ), graphene, tungsten disulphide (WS 2 ), molybdenum disulphide (MoS 2 ), black phosphorus (BP) as well as SWNTs, among many others [1][2][3][4][11][12][13][14].…”

“…They possess a sturdy mechanical strength, as well as higher thermal stability and damage threshold as compared to SWCNTs. Having multiple walls has made them capable of absorbing more photons energy per nanotubes [8].…”

Dual-loss-modulated passively Q-switched Tm:LuAG laser with multi-walled carbon nanotube and monolayer graphene

“…However, most of the pulse durations obtained from graphene or CNTs Q-switched solid-state bulk 2 μm lasers were beyond 500 ns [10][11][12][13]. For CNTs, the increase in the layer numbers can enhance the mechanical strength, the thermal stability as well as the laser damage threshold, which are of great importance for short-pulse operation [15], while for graphene, the increase in the layer numbers may increase the nonsaturable loss, which would decrease the modulation depth [16]. Since the pulse width is directly interrelated to the cavity round trip time and inversely proportional to the modulation depth of the SA Abstract By simultaneously using a multi-walled carbon nanotube (MWCNT) and a monolayer graphene saturable absorber (SA) in the cavity, a laser-diodepumped dual-loss-modulated passively Q-switched Tm:LuAG laser at 2 μm is demonstrated for the first time.…”