Ytterbium doped and co-doped Q-switched fiber lasers utilizing passive saturable absorbers

Q-switched 2 micron fiber laser is a new area of research. Q-switching using passive technique by means of saturable absorber is quite rare in the research work. A stable passive Q-switched lasers operating at 1 micron, 1.5 micron and 2 micron wavelength regions were demonstrated using Ytterbium doped, Erbium-Ytterbium co-doped and Thulium-Ytterbium co-doped fibers, respectively as the gain medium. Carbon nanotubes and graphene based saturable absorbers (SA) were explored as the passive Q-switcher in the proposed lasers. The Q-switched Ytterbium doped fiber laser (YDFL) operating at 1060.2 nm was realized using a multi-walled carbon nanotubes / PEO saturable absorber. The repetition rate of the laser were varied from 7.92 kHz to 24.27 kHz by varying the pump power from 53.42 mW to 65.72 mW. At the 59.55 mW pump power, the lowest pulse width and the highest pulse energy were obtained at 12.18 μs and 143.5 nJ, respectively. The YDFL was then used to demonstrate an all-fiber based MOPA system where the maximum pulse energy of 354.2 nJ was obtained at the maximum cladding pump power of 800 mW. The Qswitching of Erbium-Ytterbium fiber laser (EYFL) was demonstrated using a multilayer graphene film based saturable absorber. The proposed laser was operated at 1532.5 nm and self-started at pump threshold of 44 mW to produce Q-switching pulse with repetition rate of 12.33 kHz and pulse width of 9.36 μs. At the maximum pump power of 78 mW, the maximum pulse energy of 5.8 nJ and the shortest pulse duration of 2.68 μs were achieved. Multi-wavelength and Q-switched fiber lasers were also demonstrated based on the newly developed octagonal shape double-clad Thulium-Ytterbium fiber (TYF) operating at 2 micron wavelength region. By incorporating the home-made multi-wall carbon nanotubes saturable absorber (MWCNTs SA) in the ring cavity, a Q-switching pulse train operating at 1983.4 nm was successfully demonstrated. By varying the 905 nm multimode pump power from 1570 to 1606 mW, the pulse repetition rate increased from 27.4 to 37.8 kHz and the pulse width fluctuated from 3.8 μs to 4.9 μs. The maximum pulse energy of 10.6 nJ was obtained at pump power of 1570 mW. Besides showing good Q-switching performance, the proposed saturable absorbers are easy to fabricate and inexpensive

Efficiency of output power in ring cavity of erbium doped fiber laser

The output power and efficiency of erbium doped fibre laser (EDFL) based on ring configuration have been proposed and presented. Erbium doped fibre laser is demanded in fibre laser technology as it features 1.5 micron wavelength region which has attracted much interest due its potential in many applications such as optical communication and optical sensor application. Therefore, an optical hands-on rare earth doped fibre laser experiment made in ring cavity has been proposed and experimentally demonstrated. This experiment is achieved by utilizing erbium (Er3+) doped fibre as its gain medium in the cavity. The fibre ring cavity laser consist of EDFL, 980 nm pumping source laser diode, wavelength division multiplexing (WDM), output coupler, OSA, and optical power meter. The results for optical spectrum laser threshold and efficiency of EDFL ring cavity are analysed

Dual-wavelength mode-locked laser based on evanescent field interaction with max phase saturable absorber

For the first time, we proposed a dual-wavelength laser generation with a titanium aluminum carbide (Ti3AlC2) as a saturable absorber in an erbium-doped fiber laser cavity. The saturable absorber device based on the MAX phase Ti3AlC2 deposited onto D-shaped fiber has successfully triggered a dual-wavelength laser centered at 1533 nm and 1557 nm. The elemental composition and vibrational modes of the saturable absorber were analyzed by using energy-dispersive x-ray spectroscopy and Raman spectroscopy for chemical analysis. We also captured a strong saturable absorption of 2% and a non-saturable absorption of 49.2% at the 1.55-µm, confirmed its ability to generate pulses in the near-infrared wavelength spectrum. The dual-wavelength laser owns a pulse width of 280 ns, a repetition rate of 1.887 MHz, and a signal-to-noise ratio of ~63 dB. By varying the laser diode pump from 62-90 mW, a stable dual-wavelength laser was generated with the highest single pulse energy of 2.33 nJ, which corresponded to the output power of 4.4 mW. This demonstration shows the potential of MAX phase Ti3AlC2 as a saturable absorber in an all fiber-based laser cavity

Observation of dark and bright pulses in q-switched erbium doped fiber laser using graphene nano-platelets as saturable absorber

In this paper, a passively Q-switched Erbium doped fiber laser (EDFL) by residing Graphene nanoplatelets (GnPs) embedded in polyvinyl alcohol (PVA) based saturable absorber (SA) is demonstrated. To aid the dispersion of GNPs, a surfactant is used and then it is mixed with polyvinyl alcohol (PVA) as host polymer to develop GnPs-PVA film based passive SA. The GnPs-PVA based film then integrated in laser cavity in ring cavity configuration for pulse laser generation. The experimental works show that the proposed passive SA operates at input pump power range from 77 mW to 128 mW with a tunable repetition rate from 78.4 kHz to 114.8 kHz and a shortest pulse width of 3.69 µs. The laser produces maximum instantaneous output peak power and pulse energy of 7.3 mW and 30.46 nJ, respectively and accompanied by signal to noise ratio (SNR) of 64 dB

Saff-Chol Juice: Your Healthy Drink

Atherosclerosis has been established to be an indolent inflammatory disease of the arteries which can gives rise to coronary artery disease (CAD), one of the most prevalent causes of death in developed and developing countries. Saffron, one of the world’s most expensive spices, is collected from dried stigmas of Crocus sativus L. Saffron exhibits favourable effects in the prevention or treatment of a variety of diseases including dyslipidemia, hypertension and diabetes mellitus. Our previous in-vitro work showed that Saffron downregulates gene and protein expressions of inflammation, endothelial activation and upregulate the gene of oxidative stress and inhibit monocyte- endothelial interactions which are the key events in pathogenesis of atherosclerosis. Thus, we have translated our research finding into saffron formulated drink; Saff-Chol Juice. It can be used as daily healthy drink to combat many atherosclerosis complications such as heart attack, stroke and renal failure. It is safe and easy to consume. This product may benefit patients with heart problem, hypertension and renal failure. It is also useful for smokers who is at risk to develop atherosclerosis

Samarium oxide film for picosecond mode-locked erbium-doped fiber laser

The saturable absorber device based on the samarium oxide film (Sm2O3) was employed inside the erbium-doped fiber laser (EDFL) cavity to initiate mode-locked at 1562 nm. A home-made Sm2O3-PVA had generated mode-locked laser with a pulse width of as short as 3.4 ps, corresponds to a repetition rate of 1.88 MHz. The EDFL cavity initiated stable mode-locked pulses within the pump power of 91 to 142 mW. At a maximum attainable pump power of 142 mW, a self-constructed laser cavity consumed maximum output power of 22.6 mW, corresponds to pulse energy of 12 nJ. Mode-locked EDFL generated was stable as it exhibits SNR of 68 dB and pumps efficiency of 15%. Our laser cavity was optimum as we captured stable mode-locked within a 1.55 µm region, thus open the potential for laser commercialization in the industry of micromachining and laser cutting technology. This demonstration shows the potential of samarium oxide as a saturable absorber in an all fiber-based laser cavity

Conceptual Paper on Key Factors Influencing Financing or Loan Growth in Malaysian Islamic Banks and Conventional Banks

This conceptual paper aims to develop a comprehensive framework on the key factors influencing the financing growth in Islamic banks and loan growth in conventional banks in Malaysia. This is due to the crucial role of financing or loan growth in contributing significantly to bank income and fostering the expansion of a country's economic growth. Additionally, there exists a research gap on financing or loan growth, particularly Islamic banks financing growth in Malaysia. Study on the key factors influencing financing or loan growth is also being notably limited in developing countries compared to their developed counterparts, reflecting differences in the developmental stages of banking systems. Thus, Malaysian banking system has been chosen for the study. The study proposes the use of panel data analysis, utilising data from 16 Islamic banks and 26 conventional banks in Malaysia spanning from 2007 to 2020 (14 years). The internal factors to be investigated in this study include Impaired Financing or Non-Performing Loan, Bank Size, Liquidity, Capital, and Deposit Growth, while Inflation, GDP, Dummy Government Policy, and Overnight Policy Rate will be examined as external factors. The findings from this future research are expected to give valuable insight for bankers and regulators, enabling informed actions aimed at enhancing financing or loan growth. This may involve refining credit management practices and ensuring operational enhancements, particularly within Islamic banks, for future improvement

Terahertz time-domain spectroscopy of local cow’s tissues

This study demonstrates terahertz time-domain spectroscopy characterization of animal tissues obtained from local cow at mart. Terahertz radiation is highly sensitive to the polar molecules of water, thus biological tissues with high level of hydration show strong absorption at terahertz frequencies. All tissue samples are desiccated at same temperature and time scale. The different frequency-dependent response to the terahertz radiation due to the water content are observed from the experimental data of the fat, muscle and mixed of both tissues

Length optimization of erbium doped fiber laser in ring cavity

Erbium doped fiber laser (EDFL) plays crucial role in future optical network and key enabling technology for high speed optical communication. Erbium doped fiber laser is demanded in fiber laser technology with features 1.5 micron wavelength region. The length optimization with differents length of Erbium doped fiber (EDF) is carried out to determine the efficiency of cavity. The characteristics of the output power, the lasing threshold and the effect of optimization through variation of EDF lengths are analyzed. An optical hands –on rare earth doped fiber laser experiment made in ring cavity has been proposed and experimentally demonstrated. This experiment is achieved by utilizing Erbium (Er3+) doped fiber as a gain medium in the ring cavity with the pump power of 980 nm. The characteristics of EDF length are analyzed for different lengths and the optimum length of EDF in this experiment is 3 m. The characteristics of optical spectrum and the efficiency of EDFL in ring cavity are analyzed