575 citations · 1.5k across the 17 of their papers we have counts for
11 papers · 1 filter
Ultrasensitive optical magnetometry at the microscale
Stefan Forstner, Eoin Sheridan, Joachim Knittel +4
Recent advances in optical magnetometry have achieved record sensitivity at both macro- and nano-scale. Combined with high bandwidth and non-cryogenic operation, this has enabled m…
Tapered nanofiber trapping of high-refractive-index nanoparticles
Jon D. Swaim, Joachim Knittel, Warwick P. Bowen
A nanofiber-based optical tweezer is demonstrated. Trapping is achieved by combining attractive near-field optical gradient forces with repulsive electrostatic forces. Silica-coate…
Back-scatter based whispering gallery mode sensing
Joachim Knittel, Jon D. Swaim, David L. McAuslan +2
Whispering gallery mode biosensors allow selective unlabelled detection of single proteins and, combined with quantum limited sensitivity, the possibility for noninvasive realtime…
Subdiffraction-limited quantum imaging within a living cell
Michael A. Taylor, Jiri Janousek, Vincent Daria +4
We report both sub-diffraction-limited quantum metrology and quantum enhanced spatial resolution for the first time in a biological context. Nanoparticles are tracked with quantum…
Detection of Nanoparticles with a Frequency Locked Whispering Gallery Mode Microresonator
Jon D. Swaim, Joachim Knittel, Warwick P. Bowen
We detect 39 nm x 10 nm gold nanorods using a microtoroid stabilized via the Pound-Drever-Hall method. Real-time detection is achieved with signal-to-noise ratios up to 12.2. These…
Optical lock-in particle tracking in optical tweezers
Michael A Taylor, Joachim Knittel, Warwick P Bowen
We demonstrate a lock-in particle tracking scheme in optical tweezers based on stroboscopic modulation of an illuminating optical field. This scheme is found to evade low frequency…
Fundamental constraints on particle tracking with optical tweezers
Michael A. Taylor, Joachim Knittel, Warwick P. Bowen
A general quantum limit to the sensitivity of particle position measurements is derived following the simple principle of the Heisenberg microscope. The value of this limit is calc…
Cavity Optomechanical Magnetometer
S. Forstner, S. Prams, J. Knittel +6
A cavity optomechanical magnetometer is demonstrated where the magnetic field induced expansion of a magnetostrictive material is transduced onto the physical structure of a highly…
Detection limits in plasmonic whispering gallery mode biosensors
Jon D. Swaim, Joachim Knittel, Warwick P. Bowen
We analyze a whispering gallery mode biosensor with a metallic nanorod bound to its surface. It is found that a localized surface plasmon resonance in the nanorod can reduce the op…
Yield enhancement in whispering gallery mode biosensors: microfluidics and optical forces
Kiran Khosla, Jon D. Swaim, Joachim Knittel +1
A microfluidic whispering gallery mode (WGM) biosensing system is proposed for enhanced delivery and detection of target molecules. A microtoroid resonator coupled to a tapered opt…
Interferometric detection of mode splitting for whispering gallery mode biosensors
Joachim Knittel, Terry G. McRae, Kwan H. Lee +1
Sensors based on whispering gallery mode resonators can detect single nanoparticles and even single molecules. Particles attaching to the resonator induce a doublet in the transmis…