Research Fellows Directory
Mohd Adzir Mahdi
Professor Mohd Adzir Mahdi
A laser is an optical device that drives mass of atoms to pump out millions of light particles (photons) to form an intense light beam. Typically, a conventional laser consists of a light-amplifying medium enclosed between two partial mirrors. Through stimulated emission in the light-amplifying medium, the photons bounce back and forth between the mirrors and acquire optical gain. When total gain exceeds total loss, the system is able to reach threshold and an effective laser is in action. Random lasers operate based on similar principle; albeit being mirrorless. It utilizes multiple scattering in disordered gain medium to attain feedback. Photons that propagate through disordered gain medium are scattered thousands of times in random patterns, forcing them to travel through longer paths before they exit. This gives rise to larger optical gain. The first stable random laser using conventional telecommunication fiber as the gain medium was demonstrated by Prof. Turitsyn’s research group, termed as random distributed feedback fiber laser. The random feedback mechanism is supported by intrinsic multiple scatterings in optical fiber known as Rayleigh scattering. Our research focuses on the same principle by employing distributed Erbium-doped fibers as the gain medium. The proposed architecture leads to a new concept of random lasing; coined as random distributed erbium-doped fiber laser. What makes this architecture fascinating is the signal amplification that occurs along the transmission fiber due to the homogenous distribution of the rare-earth material, a synergy between erbium and Raman amplification.
Interests and expertise (Subject groups)