OPTICAL MICROCAVITY TECHNOLOGY
In most optical measurements light passes through the sample only once, whereas optical microcavities can be used to increase the sensitivity of optical measurements by reflecting light through the sample more than 10,000 times, amplifying the signal, and allowing the measurement of very small sample volumes with high sensitivity.
This technique can be used to amplify signals from almost any type of optical technique used in chemical sensing, including absorption, fluorescence, Raman scattering, and refractive index sensing, allowing the development of compact, fast, and accurate chemical and nanoparticle sensors for use in medicine, environmental monitoring, research, bio-diagnostics and security & defence.
Optical microcavities are micron sized devices that confine light to a volume of space comparable with the optical wavelength. The optical photons occupy highly resonant states within this space and generate large electric fields which increases the strength of interaction of each photon with any molecules or particles in the microcavity.
The optical states are modified by changing the contents of the microcavity, allowing the detection of nanoparticles and chemicals that pass through it. A general figure of merit for the sensitivity enhancement provided by a microcavity is Q/V where Q is the ‘quality factor’ of the microcavity (from which Oxford HighQ derives its name), corresponding to the number of wave oscillations that occur before the light escapes, and V is the physical volume of the microcavity in units of cubic optical wavelength. For example, an Oxford HighQ microcavity may have Q ~ 10,000 and V ~ λ³, so providing a signal enhancement of about 10,000 times compared with an equivalent measurement with no microcavity.
Microcavities offer benefits for most optical measurement methods, providing a general tool for enhanced sensing.
At Oxford HighQ our mission is to leverage the sensitivity enhancements provided by optical microcavities to make better sensors for your application. Our sensor platform offers a range of potential benefits:
Higher sensitivity – a direct result of the use of microcavities. Sensitivity gains can result from both enhanced signal magnitudes and reduced background signals.
Smaller sample volumes – individual measurements require only femtolitres of fluid, making precious samples go further and allowing inline measurement with minimal ‘siphoning’.
Multi-analyte sensing – sensing several chemicals in parallel on a single device provides more information for a deeper understanding of your sample.
Compact, robust devices – our sensors utilise microfluidics and simple optics that can be packaged into a device to suit your needs.
Simpler operation – microfluidic handling allows for automated sample preparation such as on-chip mixing and reaction chemistry. This improves repeatability and reduces the need for user training.
Lower maintenance requirements – smaller sample volumes mean that refill of reagents is less frequent.
Reduced cost – the simple construction of the devices lowers the cost compared with other instruments of comparable sensitivity.
Femtoliter tunable optical cavity arrays, Optics Lett., 35, 3556 (2010).
Spectral engineering of coupled open-access microcavities, Laser and Photonics Reviews, 10, 257 (2016).
Valley-addressable polaritons in atomically thin semiconductors, Nature Photonics, 11, 497-501 (2017)
Tunable cavity coupling of the zero phonon line of a nitrogen-vacancy defect in diamond, New Journal of Physics, 17, 12, 122003 (2015)
Strong coupling between 0D and 2D modes in optical open microcavities, J. Optics, 20, 035402 (2018).