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CATEGORIES:Lectures & Presentations
DESCRIPTION:Traditional high-finesse fiber Fabry–Pérot (FP) cavities are of
 ten bulky\, expensive\, and rely on tunable laser sources. This work presen
 ts a low-cost\, portable open-fiber cavity platform based on single-pulse C
 O₂-laser micromachining\, which sculpts concave mirrors directly onto singl
 e-mode fiber end-faces. The resulting mirrors have a radius of curvature of
  approximately 160 µm and are coated for high reflectivity at 1550 nm\, sup
 porting both plane–concave and symmetric concave–concave cavity geometries.
 \n\nGaussian beam simulations covering cavity lengths of 0–160 µm (plane–co
 ncave) and 0–320 µm (concave–concave) identify design windows with mode-siz
 e mismatch below 5% and diffraction loss under 0.5 dB. A single 1 ms\, 1 Hz
  CO₂-laser pulse produces concave surfaces with <10 nm RMS roughness\, veri
 fied using a KEYENCE VK-X3000 optical profilometer. For a 100 µm cavity\, t
 he measured free spectral range is ~7.5 nm\, and the resonance envelope clo
 sely follows an Airy profile. A finesse above 50 is achieved using a fixed-
 wavelength 1550 nm laser and a piezo-driven cavity length scan.\n\nA proof-
 of-concept photoacoustic CO₂ gas sensing experiment demonstrates a two-fold
  signal-to-noise improvement compared to a commercial cavity of similar len
 gth. These results highlight the potential of CO₂-laser-fabricated fiber mi
 rrors and fixed-wavelength laser operation for alignment-free\, compact\, a
 nd field-deployable Fabry–Pérot systems.\n\nKeywords: fiber Fabry–Pérot cav
 ity\, CO₂-laser micromachining\, concave micro-mirror\, free spectral range
 \, portable gas sensing
DTEND:20250813T160000Z
DTSTAMP:20260416T171244Z
DTSTART:20250813T140000Z
GEO:38.648794;-90.30145
LOCATION:Preston M. Green Hall\, 2120A
SEQUENCE:0
SUMMARY:ESE MS Thesis – Gonghao Ge
UID:tag:localist.com\,2008:EventInstance_50446297883294
URL:https://happenings.washu.edu/event/ese-ms-thesis-gonghao-ge
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