Engineering topics

Abrahao, Raphael A. (ORCID:0000000242850367)

Publications and source records attributed to Abrahao, Raphael A. (ORCID:0000000242850367).

2 records

DOE OSTI2025

Multifrequency-resolved Hanbury Brown–Twiss effect

The Hanbury Brown–Twiss (HBT) effect holds a pivotal place in intensity interferometry and gave a seminal contribution to the development of quantum optics. To observe such an effect, both good spectral and timing resolutions are necessary. Most often, the HBT effect is observed for a single frequency at a time due to its limitations in dealing with multifrequencies simultaneously, halting and limiting some applications. Here, we report a fast and data-driven spectrometer built with a one-dimensional array of single-photon-sensitive avalanche diodes. We report observing the HBT effect for multiple frequencies at the same time. In particular, we observe the HBT effect for up to five lines of the Ne spectrum, but this can be improved upon to include more lines. Our work represents a major step in making spectral binning and multifrequency HBT more widely available. The technology we present can benefit both classical and quantum applications.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2024

Shadow of a laser beam

Light, being massless, casts no shadow; under ordinary circumstances, photons pass right through each other unimpeded. Here, we demonstrate a laser beam acting like an object — the beam casts a shadow upon a surface when the beam is illuminated by another light source. We observe a regular shadow in the sense it can be seen by the naked eye, it follows the contours of the surface it falls on, and it follows the position and shape of the object (the laser beam). Specifically, we use a nonlinear optical process involving four atomic levels of ruby. We are able to control the intensity of a transmitted laser beam by applying another perpendicular laser beam. We experimentally measure the dependence of the contrast of the shadow on the power of the laser beam, finding a maximum of approximately 22%, similar to that of a shadow of a tree on a sunny day. We provide a theoretical model that predicts the contrast of the shadow. This work opens new possibilities for fabrication, imaging, and illumination.

47 OTHER INSTRUMENTATION↗