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Supercontinuum fiber laser source for water quality and heavy metals detection

Teh P. C., Ho Y. H., Ong C. E., Lee S. C., Lo P. K., Lai K. C., Yeap K. H., Loh S. H., Teh P. S., Tey K. L.

Optica Applicata

2017

Vol. 47, nr 3

445--456

We report a compact, all fiber, 150 ps fiber master oscillator power amplifier operating at 1064 nm that has the ability of producing a maximum average output power of 2.16 W with peak power as high as 10 kW. The output from the master oscillator power amplifier is spliced with a highly nonlinear photonic crystal fiber, generating a supercontinuum with an average power of 250 mW at repetition rate of 1 MHz and spectrum bandwidth spanning from 600 to 1700 nm. The developed supercontinuum system is used to detect the presence of heavy metal contaminants in water by a simple light transmittance method to ensure that the water is free from heavy metal contaminants and safe for consumption. The supercontinuum laser source was shone onto a water sample with a detector placed at another end in order to measure the transmitted supercontinuum light. By measuring the amount of light attenuated at particular wavelength, the concentration of heavy metal contaminants present in the water sample could be determined.

Propagation in dielectric rectangular waveguides

Yeap K. H., Teh K. H., Yeong K. C., Lai K. C., Loh M. C.

Optica Applicata

2016

Vol. 46, nr 2

317--330

We present a fundamental and accurate approach to compute the attenuation of electromagnetic waves propagating in dielectric rectangular waveguides. The transverse wave numbers are first obtained as roots of a set of transcendental equations developed by matching the fields with the surface impedance of the wall. The propagation constant is found by substituting the values of transverse wave numbers into the dispersion relation. We have examined the validity of our model by comparing the computed results with those obtained from Marcatili’s equations and the finite element method. In our results, it is shown that the fundamental mode is identical with that found in a perfectly conducting waveguide. Our analysis also shows that a hollow waveguide is found to have much lower attenuation than its dielectric counterparts. Since the cutoff frequency is usually affected by the constitutive properties of the dielectric medium, for a waveguide designed for wave with the same cutoff frequency, hollow waveguides turn out to be relatively larger in size.

Stable tunable single-longitudinal-mode semiconductor optical amplifier erbium-doped fiber ring lasers for 10 Gbps transmission over 50 km single-mode fiber

Tseng C. L., Liu C. K., Lin Z. R., Chiu C. M., Lai K. C.

Optica Applicata

2010

Vol. 40, nr 4

927--933

We demonstrate a stable and tunable single-longitudinal-mode SOA-EDF ring laser for high-speed data transmission systems. The laser is constructed by incorporating an SOA into the EDF ring cavity. The SOA acts as a saturable absorption high-pass filter to suppress cavity mode partition noise at low frequencies. Such design ensures a stable and single-frequency operation for more than several hours. The ring laser has a 30 nm tuning range in the C band and a 0.8 nm wavelength spacing to match 100-GHz ITU-T grids. The variation in the maximum power is smaller than 0.02 dB and the optical signal-to-noise ratio is above 53 dB. By employing this fiber laser, a 10 Gbps non-return zero data transmission over a 50 km long single-mode fiber with a power penalty less than 2.4 dB is demonstrated.