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

Abstract

Abstract-In this work, a compact, stable dual-wavelength Qswitched laser has been demonstrated, with a multi-walled carbon nanotubes (MWCNTs) slurry as a saturable absorber (SA) which is independent of any host polymer. The MWCNTs slurry is fabricated and the peak shift is investigated using Raman spectroscopy.The passively Q-switched erbium-doped fiber laser (EDFL) oscillated simultaneously at 1532.32nm and 1556.97nm with 24.67nm peak separation, at threshold and maximum input power of 26mW and 74mW, respectively. By increasing the input pump power from 36mW to 74mW, the pulse train repetition rate increases from 25kHz to 78kHz, while the pulse width is reduced from 17.84s to 5.24μs. The generated pulse produced maximum pulse energy and maximum peak power of 11.97nJ and 2.05mW, respectively at maximum input pump power. The recorded signal to noise ratio is about 62dB and shows that the proposed MWCNTs slurry based SA is able to generate dual wavelength Qswitched pulse laser with a high stability pulse.The generation of high energy laser pulses often utilizes Q-switching fiber lasers technology that brings about various applications in many industrial and scientific sectors including laser processing, medicine, telecommunications, range finding, metal cutting and remote sensing [1][2]. Actively Q-switched fiber lasers use optical modulation devices which made them more complicated as compared to the passively Q-switching techniques. The simplicity, compactness and flexibility [3] that Q-switched fiber lasers offer, have made them preferable in laser pulse generation. A passively Qswitched fiber laser has employed different kinds of saturable absorber as a means to find the one that would best complement the characteristics of lasers.Semiconductor saturable absorber mirrors (SESAMs), single-walled carbon nanotubes (SWNTs) as well as graphene have been widely investigated in passively Qswitched EDFL. Though it is thought that the said SA is ideal with an all-fiber cavity configuration, many researches have been continuously conducted to find a better if not the best SA to surmount the drawbacks of the previous SAs. SESAMs fabrication is complex, intricate and expensive [2][3]. It also has a narrow operation waveband and limited range of optical responses. This * E-mail: fauzan.kl@utm.my resulted in restricted pulse generation [4][5]. SWNTsbased SAs though deemed to be simple and inexpensive fabrication-wise, have higher surface energy causing them to be less stable, lower damage threshold and lack reliability as well. Having a much lower saturation intensity and a higher damage threshold as compared to SWNTs, graphene is seen as a better SA as it can allow better saturable absorption as well as ultrafast recovery time [6]. However, graphene has relatively weak optical absorptions. Therefore, based on the drawbacks in the properties of the previous SAs, this research will demonstrate a compact and stable dual-wavelength Qswitched laser with MWCNTs slurries as a saturable absorber. As a family type of carbon nanotu...

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Q-Switched Erbium-Doped Fiber Laser Utilizing Tungsten Disulfide Deposited Onto D-Shaped Fiber as Saturable Absorber

“…Q-switching is one of the main techniques to produce a train of energetic short pulses [1][2][3]. It can be passively achieved by deployment of saturable absorber (SA) device inside the laser cavity [4][5][6][7][8][9]. On the other hand, research on fiber lasers have been extensively carried out in recent years due to their many advantages such as simple structure, low cost, small size, and high environmental stability.…”

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