Tapered optical fiber tip coupled to single photon emitter

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K03818
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13020:Semiconductors, optical properties of condensed matter and atomic physics-related
• Research Institution: The University of Electro-Communications
• Principal Investigator: Morinaga Makoto 電気通信大学, レーザー新世代研究センター, 准教授 (60230140)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 量子光通信 / 光ピックアップ

Outline of Final Research Achievements

We have developed a simple interface that couples photons from a micro emitter to the guided mode of a single mode optical fiber with high efficiency. One end of the optical fiber is smoothly tapered and photons from a small emitter attached at the tip emitted toward the fiber are guided without loss into the guided mode of the optical fiber. Such structures had already been fabricated, however they had excessively long thin part near the tip compared to the demand by the adiabatic condition, and thus were mechanically fragile and sensitive to the dirt. To deal with this issues, we used a focused CO2 laser beam as a heat source for the fabrication. Narrow heating width on the other hand makes smooth fabrication difficult. We scanned the laser with a Galvo mirror to make effective heating width wider for the part of the taper where adiabatic condition was critical.

Free Research Field

量子光学

Academic Significance and Societal Importance of the Research Achievements

単一光子の偏光状態を量子ビットとして用いる方式の光通信はセキュアな通信を行う量子通信として実用化に最も近い位置にあるが、その実装においては単一光子発光体からの光を伝送路である単一モード光ファイバーに効率よく結合させる必要がある。本研究で採った手法はファイバー端の加工というシンプルな構成で比較的高い結合効率を得ることができ、かつ取り回しやすいものを提供する。このデバイスは微小微弱発光体の光ピックアップとしても実用的なものである。