We describe a simple and inexpensive inline optical power monitor (OPMo) for polymer optical fibre (POF) links that are transmitting visible light carriers. The OPMo is non-invasive in the sense that it does not tap any guided light from the fibre core; rather, it collects and detects the spontaneous side-scattered light. Indeed, the OPMo indicates whether a POF transmission link has dark or live status and measures the average optical power level of the propagating signals without disconnecting the fibre link. This paper demonstrates the proof-of-principle of the device for one wavelength at a time, selected from a set of previously calibrated wavelength channels which have been found in the 45 dB dynamic range, with 50 dBm sensitivity or insensitivity by the use or non-use of a mode scrambler. Our findings are very promising milestones for further OPMo development towards the marketplace.
The use of a fluorescent fibre (15.5 mm in length) pumped in a forward direction with a 520 nm emitting LED for fast wavelength conversion to 560 nm is reported. In addition to the fact that this wavelength matches the attenuation minima of poly-methyl-methacrylate polymer optical fibres (POFs), the presented results show an external conversion efficiency of 4.7% and a bandwidth of 52.5 MHz. The device is a simple, inexpensive, compact, eye-safe and lightweight optical source at 560 nm. It can be suitable for single-channel 'long-distance' (>400 m) or WDM-based links using POFs, presenting a bandwidth-distance product of 50-100 MHz/100 m.Introduction: The C-band of silica optical fibres is centred at 1550 nm and covers the 1530-1565 nm wavelength range, presenting the minimum attenuation around 0.2 dB/km. Per-fluorinated (PF) polymer optical fibres (POFs) present minimum attenuation in an 850-1300 nm wavelength window. Suitable optical sources emitting in the near-infrared wavelengths (0.8-1.6 μm) are well developed and commercially available for silica fibres and PF POFs.Either step-index (SI) or graded-index poly-methyl-methacrylate (PMMA)-based POFs have four transmission windows assigned as blue, green, yellow/orange (560-600 nm) and red [1,2]. However, the minimum attenuation band in the 560-600 nm wavelength range is quite underexplored for data communication links [1][2][3][4] due to the fact that semiconductor compounds such as GaAsP, AlGaInP and GaP:N cannot be used to produce relatively efficient and/or fast modulating optical sources at those wavelength range. Thus, WDM-over-POF links generally discard the use of yellow/orange channels [1, 2, 5].
We explore the development of an optoelectronic probe for MF/HF/VHF (up to ∼ 37 MHz) radio frequency bands able to display the complete waveforms. It was built from simple, low cost and robust components. A passive loop antenna generates RF current which modulates an ultra-bright LED of display/illumination. The light signals are transmitted along a PMMA plastic optical fibre (POF) to an optical receiver placed in a remote site. All characterization measurements were carried out in the near-field region. Far-field radio transmissions could also be detected. The probe presented at 0.5 MHz tuning-band has shown a 62 dBµV dynamic range and was able to detect down to Hmin ∼ 0.8 nA cm−1 magnetic field amplitude. A new technique for loss compensation of the fibre link is proposed and successfully tested.
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