Browsing by Author "Tsou, Chia-Han"

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Generating High-Order Transverse Patterns in Optically Pumped Semiconductor Lasers
(2019-11-01)
Tuan, Pi-Hui
;
Hsieh, Yen-Hui
;
Tu, Chin-Wei
;
Lee, Chi-Chun
;
Tsou, Chia-Han
High-order pattern formation in an optically pumped semiconductor laser (OPSL) under a selective pumping with varying spatial overlap between the pump beam and transverse modes is explored. In contrast to transverse pattern generation by off-axis pumped solid-state lasers where the mode order can be flexibly increased, experimental results reveal that the selective pumping fails to realize high-order mode operation in OPSLs when the pump-to-mode size ratio and pump power are insufficiently large. On the other hand, several high-order patterns belonging to the Hermite-Laguerre-Gaussian (HLG) modes are observed when scanning a large-ratio pump beam to specific positions on the gain chip. These HLG modes are experimentally confirmed to mainly originate from the transverse non-uniformity of present OPSL chip, while their structural features cannot be simply correlated with the pump scanning positions. Nevertheless, it is believed that the first-time observation of pure HLG modes under the large-ratio pumping can offer useful insights into the high-order pattern manipulation in OPSLs.
Nondiffracting Superlattice Beams
(2013)
Tsou, Chia-Han
;
Wu, Tai-Wei
;
Tung, Jung-Chen
;
Liang, Hsing-Chih
;
Su, Kuan-Wei
We introduce a class of optical superlattices that are formed by two sets of wave vectors with single wave number but different azimuths. By a collimated light to illuminate a mask with multiple apertures, we generate nondiffracting superlattice beams.