The generation of dual wavelength pulse fiber laser using fiber bragg grating

A stable simple generation of dual wavelength pulse fiber laser on experimental method is proposed and demonstrated by using Figure eight circuit diagram. The generation of dual wavelength pulse fiber laser was proposed using fiber Bragg gratings (FBGs) with two different central wavelengths which are 1550 nm and 1560 nm. At 600 mA (27.78 dBm) of laser diode, the stability of dual wavelength pulse fiber laser appears on 1550 nm and 1560 nm with the respective peak powers of -54.03 dBm and -58.00 dBm. The wavelength spacing of the spectrum is about 10 nm while the signal noise to ratio (SNR) for both peaks are about 8.23 dBm and 9.67 dBm. In addition, the repetition rate is 2.878 MHz with corresponding pulse spacing of about 0.5 μs, is recorded

Configurable triple wavelength semiconductor optical amplifier fiber laser using multiple broadband mirrors

A configurable, triple wavelength fiber laser based on broadband mirrors (BBMs) and an arrayed waveguide grating (AWG) is demonstrated. The laser uses a semiconductor optical amplifier (SOA) as the primary gain medium due to its inhomogeneous broadening property that allows for the generation high intensity lasing wavelengths. The combination of the AWG and BBMs allows for triple lasing wavelength outputs with channel spacing from 0.8 to 4.0 nm to be obtained. The generated output is adjustable between 1540.6 and 1548.6 nm. The proposed SOA-based system is stable and can be used as a reserve laser source for wavelength division multiplexing systems. © 2019 Wiley Periodicals, Inc

Engineering properties of ring shaped polytheylene terephthalate (RPET) fiber self-compacting concrete

Polyethylene terephthalate (PET) bottles are plastic containers that are typically discarded, and thus, cause environmental pollution. To solve this problem, PET bottles are recycled in concrete. Previous studies have mostly used PET with straight or irregularly shaped fibers. It has been shown that PET has a weak interfacial bond with cement paste in the pullout load because of the lamellar shape of fibers. Therefore, ringshaped PET (RPET) fibers are introduced in this study to overcome the limitations of traditional straight, lamellar, or irregularly shaped fibers. RPET fibers are mainly designed with a special shape to mobilize fiber yielding rather than fiber pullout. RPET fibers are made directly from waste bottles. The diameter of RPET bottles is fixed at 60 ± 5 mm. The width of RPET fibers is fixed at 5, 7.5, or 10 mm and designated as RPET-5, RPET-7.5, and RPET-10 respectively. This study mainly determines the optimum water– binder ratio and fiber content of RPET fiber concrete (FC) through self-compacting, as well as through compressive, tensile, and toughness strength tests. A water–binder ratio of 0.55 and working ranges from 0.25% to 1% of fiber content are successfully accepted for all sizes of RPET fibers. Result of the pullout test shows that RPET fiber interfacial bond strength ranges from 0.502 MPa to 0.519 MPa for RPET-5 fiber, from 0.507 MPa to 0.529 MPa for RPET-7.5 fiber, and from 0.516 MPa to 0.540 MPa for RPET-10 fiber. This study presented that the compressive and tensile strength of RPET fiber exhibited an increase of 17.3% and 35.7%, respectively compared to normal concrete. RPET FC shows improvement in first crack load for flexural toughness strength of RPET FC with increase of 24.5% compared to normal concrete specimen. Moreover, 156 FC cylinders were used to develop new equations for predicting the compressive and tensile strengths of RPET FC via multiple regression analysis. Two equations are obtained. These equations are included in calculating compressive and tensile strength of RPET FC limited up to 28 days In conclusion, incorporating RPET fibers when recycling waste PET bottles in concrete produces FC with An improvement performance comparable to that of normal concrete

Saturable absorption measurement of platinum as saturable absorber by using twin detector method based on mode-locked fiber laser

This paper illustrates the absorption measurement of Pt as saturable absorber (SA) by using mode-locked fiber laser system. The SA is fabricated by depositing 10 nm of Pt on the fiber ferrules using sputtering method. The absorption measurement of Pt is characterised by employing a balanced twin detector method based on mode-locked fiber laser with central wavelength of 1532.25 nm, repetition rate of 2.833 MHz and pulse duration of 34.3 ns. The Pt-SA produce modulation depth of 21.9% and saturation intensity of 21.6 MW cm-2

Pulse compression in Q-switched fiber laser by using platinum as saturable absorber

This paper reported a successful demonstration on pulse compression in Q-switched fiber laser by using platinum, Pt as saturable absorber (SA). The Pt-SA is deposited through sputter deposition method. The modulation depth of Pt-SA is 46.5% with a saturation intensity of 1.4 MW cm⁻². The Pt-SA is integrated into the laser cavity to compress the pulse width in Q-switching operation. At the maximum pump power, only a small repetition rate of 29.2 kHz is needed to compress the pulse width to 1.8 μs. Meanwhile, the optical signal-to-noise ratio is about 43.0 dB. The Q-switched pulses have the maximum pulse energy of 6.5 nJ. Based on the findings, Pt has the ability to become an effective SA in generating Q-switched and pulse compression which may lead to further development of pulsed fiber laser

Saturable Absorption Measurement of Platinum as Saturable Absorber by using Twin Detector Method Based on Mode-Locked Fiber Laser

:  This paper illustrates the absorption measurement of Pt as saturable absorber (SA) by using mode-locked fiber laser system. The SA is fabricated by depositing 10 nm of Pt on the fiber ferrules using sputtering method. The absorption measurement of Pt is characterised by employing a balanced twin detector method based on mode-locked fiber laser with central wavelength of 1532.25 nm, repetition rate of 2.833 MHz and pulse duration of 34.3 ns. The Pt-SA produce modulation depth of 21.9% and saturation intensity of 21.6 MW cm-2

Experimental and Numerical Comparison Q-Switched Fiber Laser Generation using Graphene as Saturable Absorber

We demonstrated the comparison experimentally and numerically a compact Q-switched erbium-doped fiber (EDF) laser based on graphene as a saturable absorber (SA). By optically driven deposition of graphene on a fiber core, the SA is constructed and inserted into a diode-pumped EDF laser cavity. Lasing in CW region starts at 10 mW, whereas stable self-starting Q-switching with a central wavelength of 1530 nm begins at 18 mW. In this paper, at 35 mW, the maximum pulse energy reaches at 2 μJ with pulse repetition rate of 1 MHz and the narrowest pulse width is around 10 μs is obtained. The stability of the pulse is verified from the radio-frequency (RF) spectrum with a measured signal-to-noise ratio (SNR) of 48 dB. In this study, the design is compared with the simulation using the Optisystem software. The output power of the experimental study is also compared with the simulation to examine the performance

Random lasing behaviour in Al- doped ZnO nanorods

A novel method of doping Aluminum (Al) into zinc oxide (ZnO) nanorods by a simple chemical dip process is evaluated in terms of its performance in random lasing. The ZnO nanorods were synthesized by the chemical bath deposition (CBD) method at a fixed temperature of 96 °C for 3 h. The ZnO nanorods were then dipped into a fixed doping solution concentration. The dip time was varied between 0 s and 80 s and a gradual increase of Al % from the nanorod array was observed with increasing dip time. Doping ZnO nanorods in aluminum nitrate nonahydrate solution for 40 s contributes to random lasing with the lowest threshold value of 12.48 mJ/cm2 and a spectral width of 2.12 nm

Review of open cavity random lasers as laser-based sensors

In this review, the concept of open cavity lasing for ultrasensitive sensing is explored, specifically in driving important innovations as laser-based biosensors─a field mostly dominated by fluorescence-based sensing. Laser-based sensing exhibits higher signal amplification and lower signal-to-noise ratio due to narrow emission lines as well as high sensitivity due to nonlinear components. The versatility of open cavity random lasers for probing analytes directly which is ultrasensitive to small changes in chemical composition and temperature fluctuations paves the path of utilizing narrow emission lines for advanced sensing. The concept of random lasing is first explained followed by a comparison of the different lasing threshold that has been reported. This is followed by a survey of reports on laser-based sensing and more specifically as biosensors. Finally, a perspective on the way forward for open cavity laser-based sensing is put forth