Browsing by Author "Chiu, Han-Lun"

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Design of photonic crystal surface emitting lasers with indium-tin-oxide top claddings
(2018-02-05)
Huang, Shen-Che
;
Hong, Kuo-Bin
;
Chiu, Han-Lun
;
Lan, Shao-Wun
;
Chang, Tsu-Chi
Electrically pumped GaAs-based photonic crystal surface emitting lasers were fabricated using a simple fabrication process by directly capping the indium-tin-oxide transparent conducting thin film as the top cladding layer upon a photonic crystal layer. Optimization of the separate-confinement heterostructures of a laser structure is crucial to improving characteristics by providing advantageous optical confinements. The turn-on voltage, series resistance, threshold current, and slope efficiency of the laser with a 100 x 100 mu m(2) photonic crystal area operated at room temperature were 1.3V, 1.5 Omega, 121mA, and 0.2W/A, respectively. Furthermore, we demonstrated a single-lobed lasing wavelength of 928.6 nm at 200mA and a wavelength redshift rate of 0.05 nm/K in temperature-dependent measurements. The device exhibited the maximum output power of approximately 400 mW at an injection current of 2 A; moreover, divergence angles of less than 1 degrees for the unpolarized circular-shaped laser beam were measured at various injection currents. Overall, the low threshold current, excellent beam quality, small divergence, high output power, and high-operating-temperature (up to 343K) of our devices indicate that they can potentially fill the requirements for next-generation light sources and optoelectronic devices. Published by AIP Publishing.
Electrically driven GaAs-based photonic crystal lasers with ITO cladding layers
(2018-01-01)
Huang, Shen-Che
;
Hong, Kuo-Bin
;
Chiu, Han-Lun
;
Lan, Shao-Wun
;
Lu, Tien-Chang
Photonic crystal (PhC) laser, with specific merits of low astigmatism, single mode operation and integration into silicon photonic system, has been studied for many years. Compared with the edge emitting lasers (EELs), surface emitting light emitters have many advantages such as small and symmetric divergence angle and platform of array-based capability. The resonance along in-plane direction preserves the high modal gain to overcome optical loss and leads to lasing action. These photonic crystal designs which has superior essential performance to that of next-generation light sources which can propose to tunable lasing multi-wavelengths with polarization control and single-mode high beam-quality. In this report, we demonstrate the fabricated realization of a novel electrically driven high-power PhC laser incorporating indium-tin-oxide (ITO) layer as a newly designed cladding layer, which could improve the laser characteristics and achieve the much lower cost of the integrated optoelectronic application. The series of investigated actual nano fabrication lasing devices with distinct designs were observed to verify the structural parameters including grating periods and area regions by tailoring the photonic crystal structure. Based upon experimental results, lasing characteristics through high current injection at room temperature inclusive of I-V curves, L-I curves, near/far field patterns, and lasing spectra were characterized and discussed. We believe this practical watt-level light output achievement should have an impact on numerous photonic devices of the coherent operations and helpful attribution to the two-dimension integrated platform in the future.
Fabrication and Thermal Insulation Properties of Bamboo-Shaped Polymer Fibers by Selective Solvent Vapor Annealing
(2018-12-01)
Chiu, Yu-Jing
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Chiu, Han-Lun
;
Tseng, Hsiao-Fan
;
Wu, Bo-Hao
;
Li, Jia-Wei
Fibrillar materials have gained much attention recently because of their unique properties and potential applications. Although many methods have been developed to fabricate materials, it remains challenging to prepare fibrillar materials containing multicomponent materials or even with complex structures. Here, a facile strategy is developed to fabricate bamboo-shaped fibers by treating electrospun polymer core-shell fibers with solvent vapor annealing. Electrospun polystyrene (PS)/poly(methyl methacrylate) (PMMA) core-shell fibers are first prepared by electrospinning PS/PMMA blend solutions via a phase separation process. When the PS/PMMA core-shell fibers are annealed with the vapor of cyclohexane, which swells and delocalizes the PS domains selectively, the fibers transform into bamboo-shaped structures. The bamboo-shaped structures can be further examined by swelling and delocalizing the PMMA domains selectively, revealing the undulated PS structures. The thermal insulation properties of the fibers with bamboo-shaped structures are observed to be enhanced compared with the original polymer core-shell fibers.
Low threshold current photonic crystal surface emitting lasers with beam modulation capability
(2019-01-01)
Chen, Lih-Ren
;
Chiu, Han-Lun
;
Hong, Kuo-Bin
;
Lu, Tien-Chang
;
交大名義發表
We proposed a GaAs-based photonic crystal surface emitting laser with naturally formed periodic structures on the ITO top cladding layer. Low threshold current density and ability of beam modulation have been demonstrated. (C) 2019 The Author(s)
Photonic Crystal Surface Emitting Lasers with Naturally Formed Periodic ITO Structures
(2019-03-01)
Chiu, Han-Lun
;
Hong, Kuo-Bin
;
Huang, Kuan-Chih
;
Lu, Tien-Chang
;
光電工程學系
We have successfully demonstrated GaAs-based photonic crystal surface emitting lasers with low threshold current density of 0.45 kA/cm(2) by increasing the thickness of indium-tin-oxide (ITO) top cladding layer appropriately. The thicker ITO top cladding layer contributes to lower scattering loss at the surface and more uniform carrier injection. Furthermore, periodic patterns are formed naturally on the surface of ITO layer during the deposition process, resulting in the deflection of the output beam with an angle of 4.5 degrees from the vertical direction and maintaining a small divergence angle. The turn-on voltage, series resistance, and slope efficiency of the laser pumped at room temperature are 2.09 V, 5.10 Omega, and 0.24 W/A, respectively. Lasing wavelengths of different laser devices can be varied from 913.3 to 954.4 nm with several lattice constants designed from 265 to 280 nm. Based on the simple fabrication process, great energy efficiency, small divergence output, and possible beam steering capability by adjusting the periodicity of top cladding layer, such kind of lasers have great potential to be applied in the field of 3D optical sensing, such as vehicle light detection ad ranging, facial identification, environmental sensing, and so on.
Photonic crystal surface emitting lasers with novel transparent cladding layers
(2018-01-01)
Huang, Shen-Che
;
Hong, Kuo-Bin
;
Chiu, Han-Lun
;
Lu, Tien-Chang
;
光電工程學系
We reported on novel structures of GaAs-based two-dimensional photonic crystal lasers by capping the ITO transparent conducting thin film as a p-type cladding layer, and measure how greatly serving as excellent performances on high-quality operation at room temperatures.