page_title: Yasuharu Suematsu
section_title: Wavelength Tunable Laser
hierarchical_section_title: Yasuharu Suematsu / Research / Wavelength Tunable Laser
caption_attribution_description: 日本語: 世界の大陸間光海底ファイバケーブル。KDDI提供。
context_page_description: Yasuharu Suematsu is researcher and educator in optical communication technology by invention of the Dynamic Single Mode Semiconductor Lasers for actuation and following development of large capacity and long distance optical fiber communications.
context_section_description: On the other hand, the electro-tunable dynamic single mode laser, which would be a goal of the Dynamic Single Mode Laser, is, so called, a wavelength tunable laser that was proposed by Suematsu and his students in 1980 (Fig.7) and demonstrated in 1983. Later, the tuning wavelength range was increased by introduction into distributed reflectors with multi-grating pitches by Yuhichi Tohmori and Yuhzou Yoshikuni, and Larry Coldren. The electro-tunable dynamic single mode laser is especially important because it could be finely tunable and also monolithically integrable together with other photonic devices which needs the specific thermal tuning separately in the form of PICs (Photonic Integrated Circuits). It was around 2004, through the efforts of those involved, that this wavelength tunable laser was developed and used commercially in dense wavelength division multiplexing (D-WDM) systems and the optical coherent systems. It became utilized in earnest around 2010.
caption: Fig.8. International submarine cables around the world. By courtesy of KDDI.
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