Remote powering and signalling using photovoltaic power converter and reflective electroabsorption modulator
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Date
2026-01-06
Authors
Baskaran, Meena
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Publisher
University College Cork
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Abstract
Power-over-fiber (POF) technology is emerging as a promising alternative to conventional electrical power delivery. In remote access networks, photovoltaic power converter (PPC) and modulators are key components for enabling both power and data transfer over fiber. A POF link offers immunity to electromagnetic interference while providing reliable, high-resolution data transmission. These advantages make it particularly well-suited for integration into minimally invasive surgical endoscopes, where precise, real-time diagnostics are essential. As POF advances toward on-chip integration, careful modulator design becomes critical to complement PPC performance and maximize overall system efficiency.
In this work, we investigated remote powering techniques and designed a reflective surface-normal electroabsorption modulator (SNEAM) specifically for integration into distal-end imaging surgical endoscopy tool, enabling both power delivery and high-speed data transmission. The SNEAM design is based on the Quantum Confined Stark Effect (QCSE), offering high modulation depth, low power consumption, and a compact footprint. For remote powering, we explored two optical coupling methods, laser to laser edge coupling and second surface normal coupling to GaAs based PPC. We demonstrated laser to laser edge coupling using commercially available laser sources as efficient PV absorbers. By coupling a 1427 nm pump laser to a 1540 nm single-junction receiver laser, an efficiency of 33% was achieved with an open circuit voltage Voc of 0.83 V. With an 850 nm pump laser coupled to a 905 nm triple junction receiver laser, we observed efficiency of 32.7% with Voc of 3.5 V.
In the second method, the multi-segment GaAs based PPC was illuminated under surface normal incidence using Gaussian and annular beam profiles delivered through a double-clad fiber. A Gaussian illumination of 850 nm on 350 μm diameter with 4 junction PPC results in 50% efficiency and Voc of 4.56 V at 10.7 W/cm2 illumination. For higher illumination on 4 junctions PPC, the annular beam illumination holds a maximum efficiency of 47.3% and Voc of 4.76 V at 52.5 W/cm2 illumination. We present comparative studies on Gaussian and annular beam illumination for compact design strategies and future improvement scope.
The SNEAM device in the 1560 nm operation were designed and fabricated. The device was successfully transfer printed onto a targeted reflection surface to enable reflection of modulated data using the EAM device. The SNEAM device with 30 μm active diameter and overall dimensions of 80 μm × 87 μm was tested for DC and AC characterization. The DC testing shows an extinction ratio of 6 dB between bias voltages of -2 V to -7 V. The data modulation over a single mode fiber were demonstrated at 1 Gbps with a driving voltage of 6 V. The device exhibits a 3 dB electro-optic bandwidth of 9 GHz at a bias voltage of -5 V.
Future work will focus on the hybrid integration of PPCs and the SNEAM device onto a single chip, packaged with multi-core fiber that supports both channels for power and data transmission. The design will target a compact 1 mm footprint optimized for distal-end imaging surgical tools, thereby advancing the development of miniaturized, high performance diagnostic systems.
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Keywords
Power over fiber , Double clad fiber , Annular illumination , Remote powering , Photovoltaic power converter , Electroabsorption modulator , Micro-transfer printing
Citation
Baskaran, M. 2026. Remote powering and signalling using photovoltaic power converter and reflective electroabsorption modulator. PhD Thesis, University College Cork.