Dual-wavelength thulium ytterbium Co-doped fiber laser

We report on the generation of dual-wavelength fiber laser peaking at 1990.64 and 1998.92 nm with a simple ring cavity setup. The lasers are demonstrated using a fabricated silica-based nanoengineered octagonal shaped double-clad Thulium-Ytterbium co-doped fiber (TYDF) as a gain medium in a simple all-fiber ring configuration. By using 980 nm multimode laser, a stable dual-wavelength laser is generated at a threshold pump power of 1500 mW due to the non-polarization rotation (NPR) effect occurred in the cavity. The effect has been self-controlled by a suppression of mode competition in the gain medium. The result shows that the slope efficiency of the generated dual–wavelength laser is measured to be 27.23%. This dual-wavelength TYDF laser operated steadily at room temperature with a 34 dB optical signal-to-noise rati

Generation of Kelly and dip type sidebands soliton employing Topological insulator (Bi2Te3) as saturable absorber

Conventional Kelly sidebands soliton and dip-type sidebands soliton were observed with the employment of Bi2Te3 as saturable absorber (SA) in Erbium-Doped Fiber Laser (EDFL). The fabricated Bi2Te3 possessed the following characteristics: Isat 102 MW/cm2, modulation depth 41.4%, and non-saturable absorption at 10%. The Bi2Te3 solution was transferred to the end of the fiber ferrule by the optical deposition method. Conventional Kelly sidebands soliton was obtained with a fundamental repetition rate and pulse width of 24 MHz and 0.78 ps, respectively. The existing cavity length was extended and with the appropriate tuning of light polarization, dip-peak intensity soliton sidebands with bunched pulses were observed. The oscillation trace revealed the repetition rate of dip-peak intensity sidebands soliton was ascertained at 13.5 MHz, which was in accordance with the cavity length. There was a total of 144 pulses in a single bunch envelope under the maximum available pump power. With the appropriate tuning of light polarization, constructive and destructive interference between soliton and dispersive waves took place in EDFL resulting in the formation of peak intensity (Kelly sidebands) and dip-peak intensity on the soliton spectrum. To the best of the author’s knowledge, this is the first demonstration of dip-peak intensity sidebands soliton using Bi2Te3

Metal Oxide Coated Optical Fiber for Humidity Sensing Application: A Review

Humidity measurement in biomedicals, industry and electronic manufacturing applications needs an accurate and fast measurement of relative humidity by the sensor. In recent years, electronic sensors are utilized in the market, but optical humidity sensors provide several advantages over it. This paper reports the classification of optical fiber humidity sensors based on their working principles, such as fiber Bragg gratings, interferometers, and resonators. Along with the mentioned optical fiber structures, their fabrication process, equipment required for humidity sensing and the coating technique used are explained in this review. Recently, metal oxide semiconductors have been widely used as sensing material, specifically in humidity sensor applications. Thus, this paper explores optical fiber humidity sensors based on the three working principles mentioned, all of which incorporate metal oxide coatings. This review reveals that the most commonly used metal oxide for optical fiber humidity sensing is graphene oxide. This is because graphene oxide offers high sensitivity, fast response and recovery time over the other types of metal oxide. A large number of oxygen-containing groups on the surface and edge of graphene oxide also contribute to humidity sensing performance since it can permeate and absorb more water molecules. The use of hybrid nanomaterials is recently discovered and their potential as emerging coating material for optical applications are not fully exploited yet. Thus, there is still an opportunity for improvement in terms of sensitivity, response and recovery time in the context of optical fiber humidity sensor

Generation of ultra-short pulse lasers using graphene and topological insulator based 2D nanomaterials / Hazlihan Haris

In this work, fabrication of passive Saturable absorbers (SA) using 2D nanomaterials such as Graphene and Topological insulator (TIs) based was demonstrated. The fabricated passive SA was integrated in an Ytterbium-Doped Fiber Laser (YDFL) and Erbium-Doped Fiber Laser (EDFL) system for a ultra-short pulsed laser generation via mode-locking. UV-Vis-NIR spectrophotometer, Raman spectroscopy and Field Emission Scanning Electron Microscopy (FESEM) were used to verify the existence and investigate the optical properties of the fabricated SA. The SA was also characterized for nonlinear optical properties to study the SA parameters such as saturation intensity, modulation depth and non-saturable loss. The fabricated SA was applied to the end facet of a fiber ferrule, which was then mated to another clean ferrule connector to act as a passive SA, which was integrated into a ring YDFL and EDFL for pulsed laser generation. In addition, by using the Graphene SA into the YDFL cavity, a stable pulse laser was generated at 1052.89 nm wavelength with repetition rate of 4.5 MHz and pulse energy of 1.52 nJ. Next, mode locked YDFL with graphene oxide SA was generated at 1053 nm wavelength with repetition rate of 6 MHz and pulse energy of 1.65 nJ. An operating wavelength of approximately 1051 nm was generated when TI based SA (Bi2Se3) was used as a Mode-locker in a passively Mode-locked YDFL. Repetition rates is 8.3 MHz while a pulse energy of 1.5 nJ was recorded by using TI Bi2Se3 as SA. A stable Mode-locking operation was successfully obtained at the central operating wavelength of YDFL dropped from the initial 1050.28 nm with the addition of TI Bi2Te3 SA. The repetition rate of 9.5 MHz and pulse energy was 2.14 nJ. Ultra-short pulses beyond 1.5 μm region wavelength with durations below 200 fs were generated through a Mode-locked in EDFL seeded by used fabricated SA. A stable passive Mode-locked EDFL operating at 1565 nm wavelength demonstrated using graphene SA as Mode-locker. In anomalous regime with estimated group delay dispersion, GDD of -0.22 ps2, the soliton mode locked EDFL pulse was generated with repetition rate of 20.7 MHz, pulse width of 0.88 ps and pulse energy of 1.5 nJ. A stable bound soliton appeared at wavelength 1564 nm with inserting about 13.2 m single mode fiber, SMF into EDFL cavity. In the particular case there were 7 solitons in bunch with repetition rate of 11.9 MHz and anomalous regime GDD of -0.37 ps2. The pulse width of 1.04 ps and pulse energy of 1.97 nJ by using passively graphene SA as SA. Other fabricated SA (graphene oxide, TI bismuth selenide and TI bismuth telluride) were used to reliably Mode-locked erbium soliton fiber lasers producing picosecond pulses at 1.56 μm. Various modes of pulse operation were studied using the above mentioned SA. Soliton mode-mocking was realized using graphene and TIs based S

Soliton pulses generation with graphene oxide saturable absorber

Nowadays, ultrafast fiber lasers have gained tremendous interests due to their potential applications in various fields including micromachining [1], bio photonic imaging [2] and optical communication [3]. Laser can be generated by mode-locking mechanism based on either active or passive pulsing methods. Active technique synchronizes to the cavity repetition rate via an external modulator while passive technique synchronizes a within the laser resonator via an all optical nonlinear process. Due to the need for an external modulator, active pulse laser construction is rather bulky and complex in comparison to the simpler and compact construction of passive pulse laser, where its mechanism depends only on the generation of saturable absorption action. Saturable absorbers (SAs) used in passive pulse laser can be either real SAs (e.g. carbon nanotubes (CNTs), graphene) or artificial SAs (nonlinear polarization rotation (NPR)). Overall, passive technique is more cost efficient and robust compare to the active technique [4-5]

Ultrafast L Band Soliton Pulse Generation in Erbium-Doped Fiber Laser Based on Graphene Oxide Saturable Absorber

We demonstrate a simple mode-locked Erbium-doped fiber laser (EDFL) based on self-synthesized saturable absorber (SA) by combining graphene oxide (GO) and polyethylene oxide (PEO) solutions to form a GO-PEO thin film. This thin film was incorporated into an Erbium-doped fiber laser (EDFL) with a cavity length of 9 m. Our EDFL could operate at a 22 MHz repetition rate with a 0.8 ps pulse duration. The laser also showed stable soliton pulses under various laser pump power values. Our reported results show that GO-PEO SA is effective and proven as a cost-effective material for saturable absorbers for EDFLs

Switchable Brillouin frequency multiwavelength and pulsed fiber laser

Switchable single and double Brillouin multiwavelength and pulsed laser is successfully demonstrated. Brillouin spacing can be switched from single (0.08 nm) to double spacing (0.16 nm) or vice versa by swapping the ports of the coupler in the proposed configuration. The proposed configuration can also be used to produce pulsed laser by inserting a home-made carbon nanotubes saturable absorber into the laser cavity. The proposed system is very versatile and flexible as it can be used as a multiwavelength laser or pulsed laser to cater for different types of applications

Pulse generation of mode-locking fiber laser at 1.053 µM using graphene oxide film as saturable absorber

This article depicts a reliable mode-locking Ytterbium-doped fibre laser (YDFL) utilizing a saturable absorber (SA) film which was created by combining graphene oxide (GO) and polyethylene oxide (PEO) solutions. A thin film was eventually formed from the polymer composite after it was dried at room temperature. The thin film is then integrated into the YDFL cavity to initiate mode-locking process. Pulse with repetition rate of 6 MHz is observed from oscilloscope. The estimated cavity length of YDFL is calculated at approximately 25 m a total net dispersion of -20.397 ps2 /km. This proves that our self-fabricated SA is successful and is proven as an effective SA

Multi-walled carbon nanotubes saturable absorber in Q-switching flashlamp pumped Nd:YAG laser

Passively Q-switched Nd:YAG laser pumped by flashlamp is demonstrated by using a saturable absorber made of a multi-walled carbon nanotubes-polyethylene oxide (MWCNTs-PEO) film. Two positions of the film are tested in the resonator to optimize its performance. The maximum pulsed energy obtained for the Q-switching operation is 1.68 mJ corresponding to 88.36 J electrical pump energy. The pulse duration of 83.64 ns is achieved with a peak power of 20.1 kW. A MWCNTs-PEO-film is a promising saturable absorber because of its simple cavity design, reliable and low cost fabrication compared to normal nonlinear crystal absorber

Digital technologies evolution in swiftlet farming: a systematic literature review

The integration of cutting-edge technologies into swiftlet farming has greatly enhanced efficiency, productivity, and sustainability. The internet of things (IoT) provides farmers with up-to-date environmental data, enabling them to create and sustain ideal circumstances for swiftlets. Artificial intelligence (AI) enhances this process by analysing vast databases and providing farmers with well-informed choices to optimize yield. Biotechnology, by combining genetic selection and breeding programs, effectively connects with the IoT, enabling constant monitoring and control of the health and genetic traits of swiftlets. The integration of renewable energy technology seeks to diminish dependence on conventional energy sources, promoting sustainability. In this paper, a systematic review of the literature is examined the utilization of digital technology in the swiftlet farmhouse. The findings were classified into three main themes: smart monitoring and control systems, advanced bird detection techniques, and sustainable practices and innovative approaches, specifically in the manufacture of edible bird nest. This systematic literature review emphasizes the multidisciplinary nature of swiftlet farming's technological evolution, technology developers, challenges and recommendations that farmers and the industry face in their pursuit of sustainable growth