15:45 〜 16:00
▲ [16p-C301-8] Selectively Excited Higher Order Mode in a Chemically Etched Few-Mode Fiber for High Relative Humidity Measurement
キーワード：optical fiber, relative humidity, intensity measurement
A single mode-chemically etched few mode-single mode structural configuration has been utilized to demonstrate a highly sensitive and reversible high relative humidity measurement (> 70 % RH). An optimized few-mode fiber (FMF) geometry with deep-etched core (waist diameter ~ 7 µm) and coating width of ~2 µm shows a remarkable change in the output power (~ -30 dBm) for a range of RH from 70-100 %. The key reason to this maximized sensitivity appears to be the efficient and selective excitation of the higher-order coating-modes from the fundamental mode of single mode fiber (SMF) owing to the presence of steep quasi-adiabatic SMF-FMF transition region. The research problem was then analyzed on the avenue of associated theoretical considerations in order to validate the experimental data and the resulting accuracy.