1. Department of Electrical Engineering; University of Malaya; 50603 Kuala Lumpur Malaysia
2. Photonics Research Centre; University of Malaya; 50603 Kuala Lumpur Malaysia
3. Department of Electrical Engineering; UTMSPACE; University of Technology; Malaysia 54100 Jalan Semarak Kuala Lumpur Malaysia
4. Department of Physics; University of Malaya; 50603 Kuala Lumpur Malaysia