An optical-fiber-based probe for photonic crystal microcavities

• Published in: IEEE journal on selected areas in communications Vol. 23; no. 7; pp. 1321 - 1329
• Main Authors: Srinivasan, K., Barclay, P.E., Borselli, M., Painter, O.J.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-07-2005; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Cubic lattice; Holes; Joining; Lattice vibration; Microcavities; Microcavity; Optical fiber polarization; Optical fibers; Optical resonators; Optical waveguides; Personal communication networks; Photonic crystals; photonic crystals (PCs); Polarization; Probes; quantum optics; Resonance; Resonators; Studies; Wavelength measurement
• ISSN: 0733-8716; 1558-0008
• DOI: 10.1109/JSAC.2005.851212

We review a novel method for characterizing both the spectral and spatial properties of resonant cavities within two- dimensional photonic crystals (PCs). An optical fiber taper serves as an external waveguide probe whose micron-scale field is used to source and couple light from the cavity modes, which appear as resonant features in the taper's wavelength-dependent transmission spectrum when it is placed within the cavity's near field. Studying the linewidth and depth of these resonances as a function of the taper's position with respect to the resonator produces quantitative measurements of the quality factor (Q) and modal volume (V/sub eff/) of the resonant cavity modes. Polarization information about the cavity modes can be obtained by studying their depths of coupling when the cavity is probed along different axes by the taper. This fiber-based technique has been used to measure Q/spl sim/40,000 and V/sub eff//spl sim/0.9 cubic wavelengths in a graded square lattice PC microcavity fabricated in silicon. The speed and versatility of this fiber-based probe is highlighted, and a discussion of its applicability to other wavelength-scale resonant elements is given.