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Proceedings Paper

Optical-loss suppressed InGaN laser diodes using undoped thick waveguide structure
Author(s): Masao Kawaguchi; Osamu Imafuji; Shinichiro Nozaki; Hiroyuki Hagino; Shinichi Takigawa; Takuma Katayama; Tsuyoshi Tanaka
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Paper Abstract

We propose optical-loss suppressed thick-optical-waveguide (TOW) InGaN laser diodes (LDs) without operatingvoltage increase. A record high continuous-wave (CW) output of 7.2W for a single-emitting InGaN LD is achieved without thermal peak-out in the light-current curve. The TOW enables to confine major part of the propagating light into a transparent undoped region, and thus significantly reduces the optical-loss. An electron-overflow-suppression (EOS) layer placed between the waveguide layer and a p-cladding layer plays an important role to reduce the operating voltage after introduction of the undoped TOW layer. We executed a self-consisted calculation of voltage-current characteristics taking into account Schrödinger and Poisson equations in conjunction with a carrier continuity equation. The calculation result indicates possible presence of conductivity-modulation in the waveguide filled with electrons reflected backward by the EOS layer and holes injected from the p-type cladding layer. We successfully demonstrated the optical-loss suppressed operation resulting in the slope efficiency (SE) increase from 2.0W/A to 2.5W/A. It is noted that the operating voltage of the TOW LD is nearly identical to the conventional LD thanks to the above conductivitymodulation phenomenon. The presented result suggests that our TOW structure can overcome the optical-loss drawback of the InGaN LDs, and hence will lead them to the applications requiring high wattage light sources.

Paper Details

Date Published: 26 February 2016
PDF: 10 pages
Proc. SPIE 9748, Gallium Nitride Materials and Devices XI, 974818 (26 February 2016); doi: 10.1117/12.2212011
Show Author Affiliations
Masao Kawaguchi, Panasonic Corp. (Japan)
Osamu Imafuji, Panasonic Corp. (Japan)
Shinichiro Nozaki, Panasonic Corp. (Japan)
Hiroyuki Hagino, Panasonic Corp. (Japan)
Shinichi Takigawa, Panasonic Corp. (Japan)
Takuma Katayama, Panasonic Corp. (Japan)
Tsuyoshi Tanaka, Panasonic Corp. (Japan)


Published in SPIE Proceedings Vol. 9748:
Gallium Nitride Materials and Devices XI
Jen-Inn Chyi; Hiroshi Fujioka; Hadis Morkoç; Yasushi Nanishi; Ulrich T. Schwarz; Jong-In Shim, Editor(s)

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