Time-resolved optical conductivity is an often used tool to interrogate quantum materials driven out of equilibrium. Theoretically calculating this observable is a complex topic with several approaches discussed in the literature. Using a nonequilibrium Keldysh formalism and a functional derivative approach to the conductivity, we present a comparison of two particular approaches to the calculation of the optical conductivity and their distinguishing features, as applied to a pumped superconductor. The two methods are distinguished by the relative motion of the probe and gate times; either the probe or gate time is kept fixed while the other is swept. We find that both the methods result in same qualitative features of the time-resolved conductivity after pump is over. However, calculating the conductivity by keeping the gate fixed removes artifacts inherent to the other method. We provide software that, based on data for the first method, is able to construct the second approach.
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Curvature polishing for light-weight, thin reflective optics
Traditional optical manufacturing techniques such as abrasive polishing and diamond turning create precise surfaces by removing material from the optical surface of a mirror. Such techniques often require many cycles of removal and metrology and can leave surface roughness or tool marks that negatively affect the straylight properties of an optical system. These residual artifacts often necessitate expensive postprocessing such as ion beam finishing. Limiting straylight is particularly crucial in the design of reflecting coronagraphs or optical systems that are sensitive to scattered light, for example for exoplanet detection, where even low-level scattering can degrade contrast ratios below the sensitivity needed to detect exoplanets. We introduce a non-contact method for shaping thin front-surface mirrors to avoid tool artifacts. Using laser techniques to alter local surface stresses, we deterministically introduce ≥ 8 waves (632.8 nm) of shape to 2 mm thick substrates. A deterministic method for creating arbitrary surface figures is under development and calibration.
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- PAR ID:
- 10517941
- Editor(s):
- DeGroote_Nelson, Jessica; Unger, Blair L
- Publisher / Repository:
- SPIE
- Date Published:
- Journal Name:
- Joint poster session at Optica Design and Fabrication
- ISBN:
- 9781510668058
- Page Range / eLocation ID:
- 6
- Format(s):
- Medium: X
- Location:
- Rochester, United States
- Sponsoring Org:
- National Science Foundation
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