Diffuse correlation spectroscopy (DCS) is a well-established method that measures rapid changes in scattered coherent light to identify blood flow and functional dynamics within a tissue. While its sensitivity to minute scatterer displacements leads to a number of unique advantages, conventional DCS systems become photon-limited when attempting to probe deep into the tissue, which leads to long measurement windows (∽1 sec). Here, we present a high-sensitivity DCS system with 1024 parallel detection channels integrated within a single-photon avalanche diode array and demonstrate the ability to detect mm-scale perturbations up to 1 cm deep within a tissue-like phantom at up to a 33 Hz sampling rate. We also show that this highly parallelized strategy can measure the human pulse at high fidelity and detect behaviorally induced physiological variations from above the human prefrontal cortex. By greatly improving the detection sensitivity and speed, highly parallelized DCS opens up new experiments for high-speed biological signal measurement.

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We propose an on-chip integrated differential optical microring refractive index sensing platform which leverages laminar flow conditions. Close spacing between a sensing and a reference resonator, and sharing the same microfluidic channel allows the two resonators to experience similar environmental disturbances, such as temperature fluctuations and fluidic-induced transients, achieving reliable and sensitive sensing performance. We obtain a noise floor of 80.0 MHz (0.3 pm) and a bulk refractive index sensitivity of 17.0 THz per refractive index unit (RIU) (64.2 nm/RIU), achieving a limit of detection of 1.4×10(-5) RIU in a 30 min and an 8°C window.

The dynamics of living organisms are organized across many spatial scales. However, current cost-effective imaging systems can measure only a subset of these scales at once. We have created a scalable multi-camera array microscope (MCAM) that enables comprehensive high-resolution recording from multiple spatial scales simultaneously, ranging from structures that approach the cellular scale to large-group behavioral dynamics. By collecting data from up to 96 cameras, we computationally generate gigapixel-scale images and movies with a field of view over hundreds of square centimeters at an optical resolution of 18 µm. This allows us to observe the behavior and fine anatomical features of numerous freely moving model organisms on multiple spatial scales, including larval zebrafish, fruit flies, nematodes, carpenter ants, and slime mold. Further, the MCAM architecture allows stereoscopic tracking of the z-position of organisms using the overlapping field of view from adjacent cameras. Overall, by removing the bottlenecks imposed by single-camera image acquisition systems, the MCAM provides a powerful platform for investigating detailed biological features and behavioral processes of small model organisms across a wide range of spatial scales.

In a high power fiber amplifier, a frequency-chirped seed interrupts the coherent interaction between the laser and Stokes waves, raising the threshold for stimulated Brillouin scattering (SBS). Moving the external mirror of a vertical cavity surface-emitting diode laser 0.2 μm in 10 μs can yield a frequency chirp of 5 × 10 17 Hz∕s at a nearly constant output power. Opto-electronic feedback loops can linearize the chirp, and stabilize the output power. The linear variation of phase with time allows multiple amplifiers to be coherently combined using a frequency shifter to compensate for static and dynamic path length differences. The seed bandwidth, as seen by the counter-propagating SBS, also increases linearly with fiber length, resulting in a nearly-length-independent SBS threshold. Experimental results at the 1.6 kW level with a 19 m delivery fiber are presented. A numerical simulation is also presented.