Peh Chiong Teh

A simple data storage system using QR code

Due to its limited data area, QR codes are presently restricted to storing simple text messages. In this paper, we develop a novel method to expand the storage capacity of QR codes. We propose to compress the file first before encoding it into a QR code. Doing so, we would be able to store more complicated files which require more storage capacity. In our study, we show that both monochrome and colour image files, as well as, voice messages in midi format could be encoded to and decoded from the QR codes.

An 1μm all-fiber based pulsed laser system incorporating an agile waveform tailoring driver

This paper describes a 1.06μm all-fiber based pulsed laser source incorporating an agile Field Programmable Gate Array (FPGA) based driver board, which has the capabilities to generate pulses with arbitrary shapes and controllable bursts. Optical pulse durations tunable from picoseconds to nanoseconds, as well as pulse frequency adjustments from 1kHz to 1MHz can be achieved. An average optical power of 1W can be obtained from the amplified system with the output optical pulses optimized by reshaping the input pulses using this agile waveform tailoring method.

Water contaminants detection by a supercontinuum laser system

Heavy metal contaminant in the water aquifers is an environmental threat. In present study, by utilizing a broadband supercontinuum (SC) laser source, detection of the contaminants is achieved through emission of broad spectrum of lights. By measuring the amount of light transmitted through the water sample, the presence of heavy metal contaminants is thus determined. A statistical analysis is conducted to analyze the performance of water contaminants detection. Interactive effects between three independent factors namely wavelength of the SC source, concentration of the heavy metal contaminants and input power are examined. Optimal operational conditions are obtained along with longer wavelength, lesser concentration of contaminants and lower power source. Under these conditions, high detection rate could be achieved with a transmittance value at 0.751.

Compact, all fiber picosecond MOPA for supercontinuum generation

We report a compact, all fiber, 150 ps picosecond fiber Master-Oscillator-Power-Amplifier (MOPA) that is capable of producing a maximum average output power of 2.16 W with peak power excessing 10 kW. The output from the MOPA is coupled into a PCF fiber, generating a broad continuum with spectrum bandwidth spanning from 600 nm to 1700nm.

Novel Detection of Heavy Metals in Water using Supercontinuum Broadband Laser Source

We report a novel detection technique for two types of common heavy metal contaminants in water, copper sulphate and ferric chloride, by analyzing the transmittance measurement of a supercontinuum laser source onto the samples.

Flexible pulse-width tunable 1.06µm pulsed laser source utilizing a FPGA based waveform generator

This paper describes our 1.06um pulsed laser source which has the capability to generate pulses with tunable durations from picoseconds to nanoseconds. This is made possible through the use of a high speed Field Programmable Gate Array (FPGA) board to generate the required pulses/ any arbitrary waveforms. The FPGA codes are specially designed to generate very fast rise/fall times waveforms with the flexibility to vary both the pulse duration and pulse frequency in real time. These custom defined waveforms are then used to generate high intensity laser pulses when connected to a 1064nm fiber laser source. These tunable pulsed laser sources have potential industrial applications in precision laser micro machining, where the high thermal intensity of the laser pulses can be used to perform ablation, cutting, drilling or annealing of processed materials. Furthermore, by able to tailor the shape of the delivered laser pulses, this will lead to reduction in processing time, improves the efficiency of material removal and the quality of the end product. Our custom board can generate arbitrary tailored pulses as short as 200ps and the longest pulse is 200ns. The pulse repetition rate can be tuned from 20 kHz to 1MHz.