Development of small light source with extended-nano space processing

2019 Fiscal Year Final Research Report

• Project/Area Number: 18K19036
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 30:Applied physics and engineering and related fields
• Research Institution: Keio University
• Principal Investigator: Tanabe Takasumi 慶應義塾大学, 理工学部(矢上), 教授 (40393805)
• Co-Investigator(Kenkyū-buntansha): 柿沼 康弘 慶應義塾大学, 理工学部(矢上), 教授 (70407146)
• Project Period (FY): 2018-06-29 – 2020-03-31
• Keywords: 光エレクトロニクス / 量子エレクトロニクス / 光周波数コム / 微小光共振器

Outline of Final Research Achievements

We fabricated a high-Q microcavity only by cutting by using the ultraprecision machining. To date, post-polishing was needed to obtain a high Q microcavity, but we demonstrated that a smooth surface is obtained if a ductile mode cutting is applied that is realized by ultra-precision processing. The ductile mode cutting conditions were studied, and the MgF2 micro-optical resonator was fabricated only by cutting, where we achieved a Q value of 100 million. The shape of the cavity is obtained as designed. Optical parametric oscillation experiments were carried out by using micro-optical resonators of which second-order dispersion and fourth-order dispersion are designed accurately. Since the phase matching can be achieved at a wavelength far from the pump light, the signal and the idler light could be generated at frequencies interval of larger than one octave.

Free Research Field

光エレクトロニクス

Academic Significance and Societal Importance of the Research Achievements

微小光共振器を用いた光周波数コムは，高繰り返し光パルス光源として用いることができる．例えば，超高速な光通信用光源として用いれば，従来波長の数だけ必要だった光源を1台の微小光共振器光周波数コム光源で賄うことができるので，システムの消費電力を大いに削減させることができると期待される．そのような微小光共振器コムにおいては，共振器の分散制御が重要であったが，最も高いQ値が得られる結晶微小光共振器で，形状を設計通りに得る優れた手法はこれまでなかった．今回超精密加工技術をナノフォトニクス作製に適用することで，それを初めて可能とした．