Flat metaoptics devices are paving a path towards compact and integrated photonics solutions. Composed of engineered subwavelength nanostructures, they offer freedom to shape light and alleviate alignment constraints compared to traditional optics. Utilizing conventional nanofabrication methods, their potential amplifies when combined with on-chip light sources and detectors. In our study, we introduce laser-integrated dielectric metasurfaces tailored for biophotonics applications. Our goal was to sculpt the emission of vertical-cavity surface-emitting lasers by directly fabricating metasurfaces on their emitting facets. Employing unique curved GaAs metagratings, we bypass aspect ratio-dependent etching issues, achieving fan-shaped emission with a ~60° off-axis deflection in both air and glass, with deflection efficiencies of 90% and 70%, respectively. We demonstrate proof-of-principle total internal reflectance and dark field imaging of Au nanoparticles and cells incubated with them. Our illumination module allows effortless toggling between these modes and, since the laser chip is outside the field of view, it is fully compatible with conventional microscopy setups.
Recent advancements in the integration of flat metaoptic components with light sources and detectors have created exciting possibilities for developing compact optical measurement devices. We have demonstrated monolithic integration of curved GaAs metagratings on vertical-cavity surface-emitting lasers (VCSELs), creating an ultra-compact illumination module for both total internal reflection and dark field microscopy techniques. Based on an unconventional design that circumvents the aspect ratio-dependent etching problems associated with monolithic integration, our integrated metagratings VCSELs generate a quasi-collimated off-axis beam centered at 60° in air and 63° in glass and achieves relative deflection efficiencies of 90% and 70%, respectively.
Thermally driven microswimmers self-propel by con- verting a self-generated heat flow to motion. In the last decade, many studies have been performed on Janus col- loids, which absorb laser light through an active cap, resulting in a temperature gradient and corresponding thermodynamic forces along the surface [1]. Particles trapped between two fluid phases, on the other hand, are advected by the Marangoni flow due to the temperature gradient along the interface [2, 3]. Steering along a given trajectory has been implemented by dynamical feedback
[4] or spatial shaping of the laser beam [5]. Active motion arises from the creep flow along the particle surface. Its axisymmetric component results in linear motion of the Janus particle. In various instances, however, active particles show also rotational motion. Thus complex trajectories have been observed for Janus colloids carrying a metal cap of irregular shape or moving in a in non- uniform laser intensity profile [3–6].
We report a system, which combines electrochemical and surface plasmon resonance (SPR) techniques on the same sensing chip. Each channel of a four-channel laboratory SPR sensor is supplemented with two planar gold electrodes (the reference and the counter electrodes), whereas the gold layer of SPR chip is used as the working electrode. A custom electronics enables to set an arbitrary potential between the reference and working electrodes and to measure the current flow between the counter and the working electrodes. Information from standard electrochemical techniques, i.e. cyclovoltammetry and chronoamperometry can be acquired with the system while simultaneously monitoring the shift in the surface plasmon resonance. The electrochemical SPR biosensor was used to study desorption of thiolated DNA probes with a negative potential. By comparing the acquired electrochemical and SPR signals, we show that DNA probes as well as a monolayer of alkanethiols can be desorbed by applying negative potentials to the SPR chip surface. Moreover, it is shown that the DNA probes can be reabsorbed on the SPR sensor surface and the complementary DNA can be detected without loss in detection sensitivity.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.