Polarized GaN-based LED with an integrated multi-layer subwavelength structure.
A novel type of GaN-based LED with a highly polarized output using an integrated multi-layer subwavelength grating structure is proposed. Characteristics of both optical transmission and polarization extinction ratio of the polarized GaN-based LED with three different multi-layer subwavelength structures are investigated. It is found that both TM transmission (T(TM)) and the extinction ratio(ER) of the LED output can be effectively enhanced by incorporating a dielectric transition layer between the metal grating and GaN substrate with a lower refractive index than that of the GaN substrate. Flat sensitivity of the T(TM) on the period, duty cycle of the metallic grating, and the wide range of operating wavelength have been achieved in contrast to the conventional sensitive behavior in single-layer metallic grating. Up to 0.75 high duty cycle of the metallic grating can be employed to achieve >60dB ER while T(TM) maintains higher than ~90%, which breaks the conventional limit of T(TM) and ER being always a pair of trade-off parameters. Typical optimized multilayer structures in terms of material, thickness, grating periods and duty cycle using MgF(2) and ZnS, respectively, as the transition layers are obtained. The results provide guidance in designing, optimizing and fabricating the novel integrated GaN-based and polarized photonic devices.
Zhang
Guiju
G
Institute of Modern Optical Technologies and Key Lab of Modern Optical Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China.
Wang
Chinhua
C
Cao
Bing
B
Huang
Zengli
Z
Wang
Jianfeng
J
Zhang
Baoshun
B
Xu
Ke
K
D000465:Algorithms; D003198:Computer Simulation; D004867:Equipment Design; D005708:Gallium / Q000737:chemistry*; D008027:Light; D008670:Metals / Q000737:chemistry; D055095:Optics and Photonics; D017785:Photons; D012031:Refractometry
D008670:Metals; C473348:gallium nitride; D005708:Gallium