Electrical Pumped ZnO UV Random Lasers
- PDF / 945,591 Bytes
- 10 Pages / 612 x 792 pts (letter) Page_size
- 14 Downloads / 200 Views
1035-L10-01
Electrical Pumped ZnO UV Random Lasers Siu Fung Yu1, and Eunice Sok Ping Leong1,2 1 Nanyang Technological University, Singapore, 639798, Singapore 2 Electrical Engineering, Arizona State University, Tempe, AZ, 85287 ABSTRACT The realization of ZnO random cavities may be an appropriate approach to fabricate low-cost ZnO laser diodes as there is no stringent requirement in the design of the disordered media provided that they can sustain enough optical gain and feedback within the media to achieve closed-loop random lasing. However, ZnO random lasers suffer from some drawbacks such as relatively higher threshold than conventional lasers, lack of directionality and coherency light emission as well as the difficulty to realize electrically pumped ZnO random lasers. In this paper, a short review on the possibilities to realize low threshold directional electrically pumped ZnO random laser diodes.
INTRODUCTION The development of ultraviolet (UV) ZnO semiconductor lasers has shown that the use of nanocrystals to achieve random optical feedback is a more viable option [1–3]. In particular, judging by the numerous reports on ZnO random lasers, disordered gain medium proves to be an attractive method to obtain lasing out of ZnO material for the fabrication of low-cost UV lasers. Nevertheless, the studies on random lasers are still at its preliminary stage [4,5]. Most of the research has emphasized on the general properties of random laser action and more work is required to further improve the efficiency of ZnO random lasers for more practical applications. In particular, the use of scattering effect to form random cavities leads to the output emission to be emitted in all directions [4]. Therefore the amount of light collected in a specific direction will be much smaller as compared to conventional lasers. Hence, there is a need to improve the directionality of the output emission so that the collected emission is much higher. A directional beam will also allow easier beam focusing for future possible applications. Another major problem with random lasers is that many random cavities are formed and as such, many lasing modes may appear from the emission spectrum. This makes the control of the lasing behavior of random lasers difficult. Hence, it is necessary to look into ways to reduce the mode operation of random lasers and yet achieve low pump threshold and high gain. More importantly, the ultimate goal is to investigate the possibility of using random media to produce electrically pumped ZnO lasers [6]. In this paper, the possibility to realize random lasing from ZnO nano-composite disordered films is discussed. The methods to improve the lasing efficiency (i.e., reduce threshold, improve the directionality and coherence of emission light) from random lasers are also investigated. In addition, the necessary conditions to achieve electrically pumped random lasers based on ZnO nano-composite disordered films are explained.
DIRECTIONAL RANDOM LASING FROM ZnO-SiO2 NANO-COMPOSITE WAVEGUIDE The construction of Z
Data Loading...
