Spot-Size-Converter Integrated Laser Diode with Waveguide Width Abruptly Expanded Structure

Hiroyuki YAMAZAKI  Yuji FURUSHIMA  Yasutaka SAKATA  Yuichiro OKUNUKI  Yoshihiro SASAKI  Keiro KOMATSU  

IEICE TRANSACTIONS on Electronics   Vol.E83-C    No.6    pp.838-844
Publication Date: 2000/06/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Advanced Optical Devices for Next Generation High-Speed Communication Systems and Photonic Networks)
Category: Semiconductor Lasers
laser diode,  MOVPE,  spot size converter,  access network,  coupling loss,  

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We propose a device called the Waveguide width abruptly EXpanded Spot-Size-Converter integrated Laser Diode (WEX-SSC-LD) that has been designed to improve lasing characteristics by achieving a steep photoluminescence wavelength change along the cavity. The waveguide parameter was optimized by a three-dimensional beam propagation method to reduce mode conversion and absorption losses. The WEX-SSC-LD's showed superior lasing characteristics such as threshold currents of 5.8 mA at 25C and 19 mA at 85C and operation current of 57.5 mA at an output power of 10 mW for 85C. These excellent lasing characteristics were achieved due to the steeper bandgap-energy shift in the SSC section near the LD section side by introducing the WEX-SSC structure as well as the high-quality MQW active layer grown by selective MOVPE and the precisely controlled pn-pn current blocking structure. The coupling loss to normal single-mode fiber was as low as 1.8 dB while maintaining a large coupling tolerance of 1.8 µm. These excellent coupling characteristics are very promising for passively aligned optical modules.