Amplified-spontaneous-emission feedback circuit scheme for optical measurement with improved optical power resolutions

High-resolution and stable optical power measurement using a temperature controlled amplified-spontaneous-emission feedback circuit

“…The IF is equal to the slope (S) of the curve of Pout versus Pin: IF = 𝑆 ≡ d𝑃 out /d𝑃 in [6,7,9]. Fig.…”

“…The ASEFC shown in Fig. 1(b) consists of an EDF, tunable optical bandpass filter (OBPF), VOA, two optical isolators (ISOs), wavelength-selective coupler (WC), and 3-dB FC [6,10]. The EDF was a spool of 15.9 m with a diameter of 9.5 cm and was implemented in a temperature control module (T-Control) whose temperature was finely maintained constant at 25.0 ℃ using a temperature controller.…”

“…High-resolution and stable optical power measurement is crucial for highly sensitive, long-distance, wide-area, and reliable fiber-optic sensing systems [1,2]. The optical power resolution (OPR), uncertainty in other words, of an optical power meter (PM) is typically expressed in dB (or %) and has an order of 0.01 dB (or 0.23%) [3,4,5,6]. In particular, OPR depends on conditions such as the time duration of the measurement.…”

“…In particular, OPR depends on conditions such as the time duration of the measurement. Recently, we proposed a novel optical power measurement technique that can significantly improve the OPR with respect to that of a conventional PM by implementing an amplified-spontaneous-emission feedback circuit (ASEFC) [6,7,8,9,10]. Using the ASEFC technique, we improved OPRs by factors (improvement factors, IFs) approximately from 10 to 100 in some experiments.…”

“…ASEFC comprises a gain medium, an erbium-doped fiber (EDF) or an optical semiconductor amplifier operating around the lasing threshold [11]. In an earlier study [6], we measured the loss variation of an optical variable attenuator (VOA) for a short time duration less than approximately five minutes. In this study, we propose and construct a novel temperature controlled ASEFC for a long time measurement in a remote fiber-optic sensing experimental setup, and evaluate the accuracy and repeatability of the circuit.…”