Driven by the demands for speed and field of view in the holographic photostimulation community, we designed, built, and tested a liquid crystal on silicon (LCoS) spatial light modulator (SLM) with a 1536x1536 square pixel array and high-voltage LC drive. We discuss some of the engineering work that made the MacroSLM possible, including the custom FPGA board for handling huge data rates, the large pixel size for minimizing rolloff and crosstalk, and the temperature control to handle heating effects from the high-voltage controls and high-power laser illumination. We also designed an FPGA implementation of the overdrive method for increasing liquid crystal switching speed, allowing us to overcome the significant data bottlenecks that limit frame rates for large arrays. We demonstrate 500 Hz hologram-tohologram speed at 1064 nm operating wavelength, and discuss the new science that these speeds and array sizes have enabled.
The International Space Station (ISS) is an unparalleled laboratory for studying colloidal suspensions in microgravity. The first colloidal experiments on the ISS involved passive observation of suspended particles, and current experiments are now capable of observation under controlled environmental conditions; for example, under heating or under externally applied magnetic or electric fields. Here, we describe the design of a holographic optical tweezers (HOT) module for the ISS, with the goal of giving ISS researchers the ability to actively control 3D arrangements of particles, allowing them to initialize and perform repeatable experiments. We discuss the design’s modifications to the basic HOT module hardware to allow for operation in a high-vibration, microgravity environment. We also discuss the module’s planned particle tracking and routing capabilities, which will enable the module to remotely perform pre-programmed colloidal and biological experiments. The HOT module’s capabilities can be expanded or upgraded through software alone, providing a unique platform for optical trapping researchers to test new tweezing beam configurations and routines in microgravity.
Metal nanocavity-based lasers show promise for dense integration in nanophotonic devices, thanks to their compact size and lack of crosstalk. Thermal considerations in these devices have been largely overlooked in design, despite the importance of self-heating and heat dissipation to device performance. We discuss the sources of self-heating in electrically-pumped wavelength-scale nanolasers, and the incorporation of these heat sources into a heat dissipation model to calculate laser operating temperature. We apply this thermal model to an example electrically-pumped nanolaser operating at room temperature.
We demonstrate stable three-dimensional optical trapping of 780nm silica particles using a dispersion-compensated
12.9fs infrared pulsed laser and a trapping microscope system with 1.40NA objective. To achieve these pulse
durations we use the Multiphoton Intrapulse Inteference Phase Scan (MIIPS) method to compensate for the
significant temporal dispersion introduced by the trapping system. We demonstrate orders of magnitude reduction
in pulse duration at the sample, and a dramatic increase in the efficiency of multiphoton excitation at the
sample. The use of dispersion-compensated ultrashort pulses will therefore be a valuable tool for enhancing non-linear
processes in optically trapped particles. In addition, ultrashort pulses can allow the use of pulse shaping
to control these nonlinear processes, yielding the possibility of advanced applications using coherent control of
trapped particles.
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