Asymmetric laser gating for robust low power half-duplex optical link in camera-on-tip surgical endoscopes
- 1University College Cork
Abstract
Camera-on-tip surgical endoscopes for cardiovascular imaging capable of real-time hyperspectral imaging require high speed optical communication links that operate within the strict power and footprint constraints at the distal end of a surgical guidewire. To address these constraints a half-duplex reflective link was previously demonstrated in which a Surface Normal Electroabsorption Modulator (SNEAM) served as a dual-functional optical transceiver at the distal tip requiring 5 V bias voltage, which is nevertheless incompatible with low power CMOS driver technology. Additionally, practical half-duplex operation requires time coordinated gating of the up- and down-stream channels. Adopting direct laser gating introduces thermally induced wavelength chirp, producing a time-varying power penalty that erodes the available link margin. This increases the possibility of corrupted camera image frames in the upstream channel and risks misdiagnosis. In this work, a SNEAM with an optimized Fabry-Perot (FP) cavity has been designed and fabricated. The device achieves ∼10 dB extinction ratio with a 3 V pp swing and the operating bias is reduced to below 3 V, with ∼1 mW device power consumption at the distal end. A novel asymmetric gating strategy is proposed and experimentally validated, in which only the downstream laser is gated while the upstream laser operates continuously. Error free downstream operation (BER < 10 ⁻⁹ ) was experimentally validated at 0 dB downstream to upstream optical isolation. This asymmetric gating strategy improves link robustness against variable bending loss with only ∼0.2 mW additional static power overhead during the downstream time slot.
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BibTeX
@article{khan2026asymmetric,
title = {{Asymmetric laser gating for robust low power half-duplex optical link in camera-on-tip surgical endoscopes}},
author = {Asif Khan and Valentina Rajkumari and Meena Baskaran and Owen Moynihan and Cleitus Antony and James O’Callaghan and Brendan Roycroft and Kevin Thomas and Emanuele Pelucchi and Sanathana Konugolu Venkata Sekar and Stefan Andersson-Engels and Paul Townsend and Brian Corbett},
journal = {Optics Express},
year = {2026},
month = oct,
doi = {10.1364/oe.611650},
url = {https://opg.optica.org/abstract.cfm?URI=oe-34-21-38916},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Asymmetric laser gating for robust low power half-duplex optical link in camera-on-tip surgical endoscopes
AU - Asif Khan
AU - Valentina Rajkumari
AU - Meena Baskaran
AU - Owen Moynihan
AU - Cleitus Antony
AU - James O’Callaghan
AU - Brendan Roycroft
AU - Kevin Thomas
AU - Emanuele Pelucchi
AU - Sanathana Konugolu Venkata Sekar
AU - Stefan Andersson-Engels
AU - Paul Townsend
AU - Brian Corbett
PY - 2026
DA - 2026/10/06
JO - Optics Express
DO - 10.1364/oe.611650
UR - https://opg.optica.org/abstract.cfm?URI=oe-34-21-38916
AB - Camera-on-tip surgical endoscopes for cardiovascular imaging capable of real-time hyperspectral imaging require high speed optical communication links that operate within the strict power and footprint constraints at the distal end of a surgical guidewire. To address these constraints a half-duplex reflective link was previously demonstrated in which a Surface Normal Electroabsorption Modulator (SNEAM) served as a dual-functional optical transceiver at the distal tip requiring 5 V bias voltage, which is nevertheless incompatible with low power CMOS driver technology. Additionally, practical half-duplex operation requires time coordinated gating of the up- and down-stream channels. Adopting direct laser gating introduces thermally induced wavelength chirp, producing a time-varying power penalty that erodes the available link margin. This increases the possibility of corrupted camera image frames in the upstream channel and risks misdiagnosis. In this work, a SNEAM with an optimized Fabry-Perot (FP) cavity has been designed and fabricated. The device achieves ∼10 dB extinction ratio with a 3 V pp swing and the operating bias is reduced to below 3 V, with ∼1 mW device power consumption at the distal end. A novel asymmetric gating strategy is proposed and experimentally validated, in which only the downstream laser is gated while the upstream laser operates continuously. Error free downstream operation (BER < 10 ⁻⁹ ) was experimentally validated at 0 dB downstream to upstream optical isolation. This asymmetric gating strategy improves link robustness against variable bending loss with only ∼0.2 mW additional static power overhead during the downstream time slot.
SN - 1094-4087
ER -