Abstract
An elliptical monolithic bifocal zone plate as a collimating lens, whose two focal lengths in the orthogonal directions match the different beam waist positions of the fast and slow axes’ light from edge-emitting laser diodes, is proposed and experimentally demonstrated by employing femtosecond laser direct writing technology. The high-quality eight-level zone plate exhibits a diffraction efficiency of 92.9%, which is much higher than those ever reported. Shaped by the elliptical lens, the laser diodes’ divergence angles are simultaneously reduced from 65° (1134 mrad, fast axis) and 24° (418 mrad, slow axis) to 7.7 and 136.5 mrad, respectively.
© 2013 Optical Society of America
Full Article | PDF ArticleMore Like This
Yuzo Ono and Nobuo Nishida
Appl. Opt. 25(5) 794-797 (1986)
Zhen-Nan Tian, Li-Jie Wang, Qi-Dai Chen, Tong Jiang, Li Qin, Li-Jun Wang, and Hong-Bo Sun
Opt. Lett. 38(24) 5414-5417 (2013)
Natalia Trela, Howard J. Baker, and Denis R. Hall
Opt. Express 21(4) 4512-4517 (2013)