page_title: Yasuharu Suematsu
section_title: The Earliest Demonstration of Optical Fiber Communication Experiment
hierarchical_section_title: Yasuharu Suematsu / Research / The Earliest Demonstration of Optical Fiber Communication Experiment
caption_attribution_description: English: Fig.2. Principle of Single mode resonator consisted of two distrusted reflectors connected with phase shift of integer multiple of Π/2, for Dynamic Single Mode (DSM) Lasers, in 1974
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: The earliest demonstration of optical fiber communication was performed by Suematsu and his students, in May 26, 1963, in the occasion of open house of the Tokyo Institute of Technology (Fig.1). 
  
  The light source was helium-neon gas laser, the modulator was hand made modulator by use of ADP crystal, applied signal voice voltage of 1.200 volts, for polarization rotation in response to voice signal, the optical bundle glass fiber for the transmission medium, and the photomultiplier tube for detector. The original ADP reserved in desiccator as well as the replica of that experiment, restored in 2008-7 as shown in Fig.1, were registered as a Future Technology Heritage, at the National Museum of Science, Japan, in 2019.
caption: Fig.2. Principle of Single mode resonator consisted of two distrusted reflectors connected with phase shift of integer multiple of Π/2, for Dynamic Single Mode (DSM) Lasers, in 1974.
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