Fig. 2: Performance of the plano-concave microcavities.
From: Silicon microcavity arrays with open access and a finesse of half a million
a Spectrum of a microcavity showing the free spectral range (FSR) as well as higher-index modes which are used to determine the radius of curvature (see Methods). The inset shows the lowest-order mode. b A cavity ring-down measurement yields a lifetime of (13.6 ± 0.3) ns. The inset shows a single scan over the cavity resonance recorded with an applied laser frequency sideband-modulation of 350 MHz. The frequency scale given by the resulting sidebands yields a linewidth of κ/2π = (6.77 ± 0.86) MHz. With the FSR = 7.23 THz determined as in (a), we measure a finesse of F = (5.3 ± 0.6) × 105 from the linewidth scan and F = (6.2 ± 0.2) × 105 for the ring-down measurement. The uncertainties are the standard deviations over 75 and 992 measurements for the spectral and ring-down measurements, respectively. c Distribution of the finesse over an array of 100 microcavities. d Cumulative distribution of the finesse values. A resonance was found for 88 out of 100 cavities. The bars show the probability for all cavities (blue bars) and for functioning cavities (green bars). e Distribution of losses that we find in addition to the specified 5 ppm transmission of the mirror coatings
