MISSION

Hybrid integration of quantum cascade lasers with germanium-on-silicon waveguides for mid-infrared sensing applications

Rachel — Mon, 05 Oct 2026 12:49:41 +0000

We present a scheme for hybrid integration of quantum cascade laser bars with germanium-on-silicon waveguides operating in the mid-infrared. The laser bars are flip-chip bonded onto a germanium-on-silicon target chip without active alignment, achieving end-fire coupling efficiencies of up to 50% (3.03 dB loss) in pulsed operation. Optical power estimates indicate over 50 mW is coupled into the waveguide. The passive alignment approach, combined with a CMOS-compatible photonic integrated circuit fabrication process, offers a scalable pathway to fully integrated mid-infrared photonic systems for sensing, free-space communications, and the realization of novel light sources.

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Recent progress in group IV mid-infrared photonic devices and applications

MISSIONstaff — Tue, 07 Jul 2026 08:20:57 +0000

Apologies for the short notice but I will present a version of the attached slides at the ICTON conference next week. It is a summary of recent research from Goran’s group.

All material has been published before so it contains no new results.

I will likely improve the slides but I won’t add additional content.

Please respond by: 13/07/2026
File Upload: ICTON-2026-Rowe

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Metasurface-Enhanced Molecular Absorption at Mid-Infrared Wavelengths for Therapeutic Drug Monitoring

MISSIONstaff — Thu, 12 Feb 2026 13:12:13 +0000

Therapeutic drug monitoring (TDM) is the clinical practice of measuring specific drugs at designated intervals to maintain a constant concentration in a patient's bloodstream. However, detecting clinically relevant levels (typically in the μg/ml range) remains challenging outside the laboratory, as current analytical methods use elaborate sample preparation protocols and complicated measurement procedures. Here, we present a metasurface-assisted FTIR approach using dried samples that enhances molecular absorption by aligning their vibrational modes with the metasurface resonance; the metasurface supports a guided-mode resonance that hybridises with the vibrational frequency of the drug molecule, thereby increasing the effective absorbance significantly. The metasurface topology also promotes ordered drug crystallisation in regions with the strongest light-matter interaction, further contributing to the absorption enhancement. Using this design, we are able to consistently detect phenytoin in serum below the therapeutic range of 10-20 µg/ml by achieving a limit of detection (LoD) of 1.4 μg/ml, which is limited by the drying process. This demonstration of TDM at concentrations in the sub µg/ml level highlights the significant potential for metasurface-enhanced spectroscopy and offers a path toward compact, high-performance infrared sensors for healthcare applications.

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Liquid biopsy for lung cancer detection in a high-risk cohort using machine learning-assisted ATR-FTIR spectroscopy

MISSIONstaff — Tue, 10 Feb 2026 09:42:05 +0000

A draft of an article for submission to the Journal of Biomedical Optics. The paper has gone through one round of revisions from a statistician from the medical team and is now with the clinicians for additional feedback. I expect the engineering and machine learning aspects to stay the same but the message/positioning of the interpretation may change in response to the additional feedback.

Please respond by: 09/03/2026
File Upload: JBO-v3-clean

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Mid-infrared germanium-on-silicon waveguide sensor for therapeutic drug monitoring of phenytoin

MISSIONstaff — Tue, 10 Feb 2026 09:38:34 +0000

A draft of an article for submission to ACS Photonics or ACS Sensors. Some minor changes will be made in response to feedback from JSW (his comments are contained in the manuscript) but the main content should stay the same.

Please respond by: 09/03/2026
File Upload: ACS-Photonics-v05-sharing

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Hybrid Integration of Quantum Cascade Lasers with Germanium on Silicon waveguides for Mid-Infrared Sensing Applications

MISSIONstaff — Thu, 06 Mar 2025 16:13:37 +0000

Draft of paper for suggestions and approval

Please respond by: 14/03/2025
File Upload: Flip_paper_06Mar25

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Working draft – flip chip

MISSIONstaff — Tue, 10 Dec 2024 15:36:32 +0000

Working draft, pending authors comments and revisions.
Will update and upload again after revisions.

Please respond by: 23/12/2024
File Upload: QCL Flip_v16

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Protocol for Therapeutic Drug Monitoring Within the Clinical Range Using Mid-infrared Spectroscopy

Rachel — Thu, 21 Nov 2024 10:23:00 +0000

Therapeutic drug monitoring (TDM), which involves measuring drug levels in patients’ body fluids, is an important procedure in clinical practice. However, the analysis technique currently used, i.e. liquid chromatography–tandem mass spectrometry (LC–MS/MS), is laboratory-based, so does not offer the short response time that is often required by clinicians. We suggest that techniques based on Fourier transform infrared spectroscopy (FTIR) offer a promising alternative for TDM. FTIR is rapid, highly specific and can be miniaturized for near-patient applications. The challenge, however, is that FTIR for TDM is limited by the strong mid-IR absorption of endogenous serum constituents. Here, we address this issue and introduce a versatile approach for removing the background of serum lipids, proteins and small water-soluble substances. Using phenytoin, an antiepileptic drug, as an example, we show that our approach enables FTIR to precisely quantify drug molecules in human serum at clinically relevant levels (10 μg/mL), providing an efficient analysis method for TDM. Beyond mid-IR spectroscopy, our study is applicable to other drug sensing techniques that suffer from the large background of serum samples.

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Mid-infrared silicon photonics: from benchtop to real-world applications

Rachel — Fri, 04 Oct 2024 13:40:06 +0000

Silicon photonics is one of the most dynamic fields within photonics, and it has seen huge progress in the last 20 years, addressing applications in data centers, autonomous cars, and sensing. It is mostly focused on the telecommunications wavelength range (1.3 and 1.55 µm), where silicon becomes transparent. In this range, there are excellent light sources and photodetectors, as well as optical fibers operating with extremely low losses and dispersion. It is a technology that hugely benefits from the availability of complementary metal–oxide–semiconductor (CMOS) fabrication infrastructure and techniques used for microelectronics. Silicon and germanium, as another CMOS compatible group IV material, are transparent beyond the wavelength of 2 µm. The mid-IR wavelength range (2–20 µm) is of particular importance as it contains strong absorption signatures of many molecules. Therefore, Si- and Ge-based platforms open up the possibility of small and cost-effective sensing in the fingerprint region for medical and environmental monitoring. In this paper, we discuss the current mid-IR silicon photonics landscape, future directions, and potential applications of the field.

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Sub-wavelength gratings in silicon photonic devices for mid-infrared spectroscopy and sensing

Rachel — Fri, 04 Oct 2024 13:33:01 +0000

Mid-infrared spectroscopy enabled by silicon photonics has received great interest in recent years as a pathway for a scalable sensing technology. The development of such devices would realise inexpensive and accessible instrumentation for a wide variety of uses over numerous fields. However, not every sensing application is the same; to produce sensors for real-world scenarios, engineers need flexibility in device design but also need to maintain compatibility with scalable fabrication processes. Sub-wavelength gratings can offer a solution to this problem, as they enable the engineering of optical properties using standard fabrication techniques and without requiring new materials. By using sub-wavelength gratings, specific design approaches can be tailored to different applications, such as increasing the interaction of a sensor with an analyte or broadening the bandwidth of an integrated photonic device. Here, we review the development of sub-wavelength grating-based devices for mid-infrared silicon photonics and discuss how they can be exploited for spectroscopic and sensing devices.

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