Study of Multiwavelength Fiber Laser in a Highly Nonlinear Fiber

A multiwavelength fiber laser in linear and ring cavity have been successfully developed and demonstrated in numerical and experimental method. The multiwavelength fiber laser developed is incorporating with the nonlinearity of a short section of highly nonlinear fiber (HNLF) in order to suppress the homogeneous broadening effect of erbium-doped fiber amplifier (EDFA) within the gain medium. The performance aspects such as maximum number of lasing lines generated, maximum output power produced, wavelength span covered, maximum gain obtained, and signal-to-noise ratio have been successfully investigated and analysed. The linear cavity fiber laser is observed to have more number of lasing lines generated with higher output power and wider span of wavelength when compared to ring cavity fiber laser. The output spectrum from experimental method seems to have greater performance than numerical method where 11 lasing lines in the range from 1586 nm to 1596 nm with highest output power -22.40 dBm and SNR of 43 dB is obtained for experimental method while only 4 lines generated in 1595 nm to 1594 nm wavelength range with highest output power of 0.18 dBm and SNR of 75.42 dB

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

Determination of larval instar of Bactrocera papayae (Diptera : Tephritidae) on guava, Psidium guajava, Linn. based on morphometric characters

Morphometric characters such as length and width of the Bactrocera papayae larvae could be used to determine the larval instars at their immature stage. Observation in this study indicated that B. papayae underwent three larval instars. The duration for the first instar, second and third instar was 4,4 and 7 days respectively. There was a significant difference in the length and width within larval instars of B. papayae. After hatching, the length of the larvae was 1.04 mm and the longest could reach up to 8.32 mm while the width starts from 0.18 mm and could reach up to 2.08 mm before completing all instars during the immature stage. Means length of the larvae were 1.27 ± 0.03, 4.33 ± 0.05 and 7.84 ± 0.07 mm whilst means width were 0.23 ± 0.01, 1.04 ± 0.01 and 1.85 ± 0.03 mm for the first instar, second instar and third instar respectively. Moulting process of the larvae occurred twice between day-4 and day-5 and also between day- 8 and day-9

The effects of worked examples presentation on sub-cognitive loads

One promising technique for helping students in fulfilling complex problem solving tasks is through learning with worked example. Although worked example approach is the most prominent technique discussed in the literature of cognitive load theory, there is still very little scientific understanding of managing the students’ sub-cognitive load, namely intrinsic, extraneous and germane load on different complexity of worked example approach especially in engineering domain. Thus, this study was conducted to investigate the effects worked examples presentation on sub-cognitive loads among electrical engineering students. In this research, the worked examples were presented in three different sequences: (i) all examples were of same level of difficulty (ii) from difficult to easy example; (iii) from easy to difficult example. Data were collected from 82 students (Condition (i) =27; Condition (ii) = 34; condition (iii) = 21) of Diploma in Electrical Engineering Program at three selected polytechnics. The inventory tool of sub cognitive load were given to students after each teaching and learning session ends. The findings suggested that worked examples presented in easy to difficult format could be one of the approaches that is more efficient to manage students’ cognitive load and effective to be applied in engineering lesson

Generation of four-wave mixing in a highly non-linear optical fiber using a tunable dual wavelength fiber laser source

In this paper, we demonstrate a Four Wave Mixing (FWM) effect in a highly nonlinear single mode optical fiber. A tunable dual-wavelength fiber laser is used to provide the pump and signal probe to generate partially degenerate FWM. Calculations using coupled differential equations and experimental results in the generation of FWM were analyzed. We observed that FWM conversion efficiency depends more significantly on the wavelength detuning between pump and signal wavelength as compared to zerodispersion wavelength. The tunability is achieved using an arrayed waveguide grating which provides different wavelength combinations of the dual-wavelength fiber laser output and can be tuned from 1530.47nm to 1548.61nm with a spacing of 100GHz. The highly nonlinear fiber has a nonlinear coefficient, γ of 10.8 W-1km-1 . Hence, to achieve higher FWM output power the pump power of the dual wavelength fiber laser has to be higher than that of the signal probe. The optimum measured values of pump and signal power are +13.3dBm and +5dBm respectively, limited buy the current experimental setup

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

A sensitive acoustic sensor using fiber bragg grating based on strain compensation

An acoustic sensitivity single ring fiber sensor with enhanced pressure sensitivity is designed by using Fiber Bragg Grating (FBG). Measurement sensitivity of the this fiber sensor is 0.3714 με/Hz. This sensor exhibited a good acoustic sensitivity, showing that the sensor has good sensing properties for the detection of the acoustic signals

Growth and development of Bactrocera papayae (Drew & Hancock) feeding on guava fruits

Asian Papaya Fruit Fly, B. papayae (Drew & Hancock) undergoes four stages (egg, larva, pupa and adult) during its growth and development. In this study, observation showed that the egg's stage took 1.16 ± 0.00, larva's stage took 12.02 ± 0.13 and pupa's stage took 7.03 ± 0.08 days before the emergence of the adults. The male adult survived for 21.97 ± 2.69 days whilst the female 19.19 ± 1.50 days. It was observed that the eggs laid in a cluster, range between 10 - 50 eggs per cluster. The length and width of the individual egg observed were 1.12 ± 0.03 mm and 0.20 ± 0.00 mm respectively. The percentages of the survived individual larva decreased from the first instar until third instar. In the observation, the length and width of the larva reached 7.77 ± 0.08 mm and 1.84 ± 0.03 mm respectively. Pupae were observed changing in colour from pale yellow to dark brown. The length and the width of the pupae observed were 6.78 ± 0.16 mm and 2.90 ± 0.02 mm. The longevity of the adult B. papayae (Drew & Hancock) was influenced by the diets they consumed, the presence of other individuals, wideness of the areas, differences in times taken in different stages and temperature in the laboratory

Passively Q-Switched pulse erbium doped fiber laser using Antimony (III) Telluride (Sb2Te3) thin film as saturable absorber

This paper demonstrates on an antimony telluride (Sb2Te3) thin film sandwiched between two fiber ferrule as saturable absorber for Qswitched pulsed Erbium doped fiber (EDF) laser. The saturable absorber is fabricated by dissolving Antimony (III) Telluride powder into PVA solution and dry in the ambient temperature for 48 hours. Then, 1 mm2 x 1 mm2 Sb2Te3-PVA film based saturable absorber is sandwiched in between FC/PC ferrule for Q-switched laser generation. The modulation depth of the Sb2Te3 is measured as 28.01% with input intensity 0.02 MW/cm2 . The developed passive saturable absorber integrated in EDF laser in ring cavity and the characterised pulse is with repetition rates of 30.21 kHz, shortest pulse width of 3.26 µs and signal-noise-ratio (SNR) of 42 dB. The maximum output pulse energy is achieved at pump power 69.5 mW with 29.5 nJ and the output power 0.89 mW