Photonic coherence effects from dual-waveguide coupled pair of co-resonant microring resonators: erratum.

This erratum reports a correction of a typographical error in the theoretical study of coupled optical microring resonators [Opt. Express23, 12573-12587 (2015)]. The results and conclusions of the published work remain valid.

Photonic coherence effects from dual-waveguide coupled pair of co-resonant microring resonators.

We theoretically describe photonic manifestations of electromagnetically induced transparency (EIT) and absorption (EIA) using co-resonant coupled microresonators (CMRs) as opposed to detuned CMRs explored previously. Here the coherent optical interactions between the two resonators are mediated via two adjacent waveguides and the photonic EIT and EIA are achieved by coupling two identical resonators to the waveguides with equal strength, although this coupling is distinct for each waveguide. Using co-resonant CMRs based on either identical or distinct intrinsic quality factor (Q) resonators, these effects may be obtained in both transmission and reflection. We elucidate origin of the sharp features in the spectra of co-resonant CMRs. Furthermore, we demonstrate tunability of these features using Q-tunable resonators, which may lead to tunable slow and fast light effects. The theoretical model described here greatly simplifies accurate numerical studies of coupled-resonator effects, as no additional calculations are required to account for the waveguide dispersion.

All-optical electromagnetically induced transparency using one-dimensional coupled microcavities.

We report the first experimental realization of all-optical electromagnetically induced transparency (EIT) via a pair of coherently interacting SiO2 microcavities in a one-dimensional SiO2/Si3N4 photonic crystal consisting of a distributed Bragg reflector (DBR). The electromagnetic interactions between the coupled microcavities (CMCs), which possess distinct Q-factors, are controlled by varying the number of embedded SiO2/Si3N4 bilayers in the coupling DBR. In case of weak microcavity interactions, the reflectivity spectrum reveals an all-optical EIT resonance which splits into an Autler-Townes-like resonance under condition of strong microcavity coupling. Our results open up the way for implementing optical analogs of quantum coherence in much simpler one-dimensional structures. We also discuss potential applications of CMCs.

Saturated absorption spectroscopy of acetylene gas inside large-core photonic bandgap fiber.

Saturated absorption spectroscopy is performed on the acetylene nu(1) + nu(3) band near 1532 nm inside photonic bandgap fibers of small (approximately 10 microm) and large (approximately 20 microm) core diameters. The observed linewidths are narrower in the 20 microm fiber and vary from 20 to 40 MHz depending on pressure and power. Variations in the background light transmission, attributed by others to surface modes, are significantly reduced in the 20 microm fiber. The optimum signal for use as a frequency reference in a 0.8 m long, 20 microm diameter fiber is found to occur at about 0.5 torr for 30 mW of pump power. The saturation power is found by modeling the propagation and attenuation of light inside the fiber.

Wet-etch optimization of free-standing terahertz frequency-selective structures.

Free-standing frequency-selective surfaces consisting of approximately 10-microm-thick copper films with cross-aperture arrays are found to be tunable toward lower frequencies by means of wet chemical etching. Center frequencies were tuned from 1.57 to 1.53 THz while maintaining high transmittance. Wet etching also adjusts bandwidth, peak transmittance, and sidelobe transmittance. The advantage of the wet-etch technique is demonstrated by employment of these devices as bandpass filters for difluoromethane-based terahertz lasers. Adjustment in aperture dimensions because of etching results in suppression of a competing laser line (133.93 microm) by 15 dB while maintaining high transmittance at the operating wavelength of 192.06 microm.