A highly stable mode-lock fiber laser with a thin film coating of graphene oxide (GO) nanoparticles on a D-shaped fiber is proposed and demonstrated. The GO-coated D-shaped fiber, which serves as the cavity’s saturable absorber (SA), is fabricated by drop-casting GO nanoparticles on the smooth and consistently polished area of the D-shaped fiber made using a disk-polishing machine. Mode-locking is induced through the interaction of the evanescent field from the D-shaped fiber and GO nanoparticle layer. The cavity has a length of 12.5 m with a fundamental frequency of 16.5 MHz and operates in the anomalous dispersion regime. Stable soliton mode-locking is obtained above a pump power of 76.6 mW, with a central lasing wavelength of 1555.7 nm and well-defined Kelly’s sidebands. The generated pulses have a repetition rate of 16.5 MHz and pulse duration of 1.18 ps over a pump power range of 76.6 to 280.5 mW, with only minor fluctuations observed. A signal-to-noise ratio of 58.3 dB is computed, indicating a highly stable output. The proposed SA fabrication technique provides a simple, cost-effective, and consistent method of generating mode-locked pulses in fiber lasers.
A simple sensor is proposed and demonstrated using a silica tapered fiber for sensing different concentration of potassium in de-ionized water. The tapered fiber is fabricated using a flame brushing technique to achieve a waist
diameter and length of 10 μm and 80 mm, respectively. For a concentration change from 0 to 50 %, the ouput signal of the sensor decreases exponentially from -10.04 dBm to -11.11 dBm with linearity of more than 92%. The increment of potassium concentration increases the refractive index of the solution, which in turn reduces the index difference
between core and cladding of the tapered fiber and thus allows more light to be leaked out from the fiber. This new
potassium monitoring system provides numerous advantages such as simplicity of design and low cost of production.
In this paper, a novel optical approach is proposed and demonstrated for the non-contact measurement for the thickness
of silica thick films. This approach is based on the principal of an optical based displacement sensor. The calibration
curve for the measurement of the thickness of an unknown sample is obtained using four sample with known thicknesses
of 6.90, 10.23, 19.69 and 25.47 μm respectively. As compared to a prism coupler, which is assumed to provide the most
precise measurement of thick film thicknesses, the proposed system has an error of approximately 8%. The proposed
method is able to provide a simple, low cost and time saving approach in measuring thick films thicknesses during
The purpose of this study is to investigate the potential of intensity modulated fiber optic displacement sensor scanning system for the imaging of dental cavity. Here, we discuss our preliminary results in the imaging of cavities on various teeth surfaces, as well as measurement of the diameter of the cavities which are represented by drilled holes on the teeth surfaces. Based on the analysis of displacement measurement, the sensitivities and linear range for the molar, canine, hybrid composite resin, and acrylic surfaces are obtained at 0.09667 mV/mm and 0.45 mm; 0.775 mV/mm and 0.4 mm; 0.5109 mV/mm and 0.5 mm; and 0.25 mV/mm and 0.5 mm, respectively, with a good linearity of more than 99%. The results also show a clear distinction between the cavity and surrounding tooth region. The stability, simplicity of design, and low cost of fabrication make it suitable for restorative dentistry.
Conference Committee Involvement (1)
Third International Seminar on Photonics, Optics, and Its Applications (ISPhOA 2018)