Experimental demonstration of the slow group velocity of light in two-dimensional coupled photonic crystal microcavity arrays

Slow-light devices are able to significantly enhance light-matter interaction due to the reduced group velocity of light, but a very low group velocity is usually achieved in a narrow bandwidth, accompanied by extreme sensitivity to imperfections that causes increased disorder-induced attenuation. Recent theories have suggested an ideal solution to this problem - unidirectional chiral photonic states, previously discovered in structures known as photonic topological insulator...

One of the major advances needed to realize all-optical information processing of light is the ability to delay or coherently store and retrieve optical information in a rapidly tunable manner. In the classical domain, this optical buffering is expected to be a key ingredient to managing the flow of information over complex optical networks. Such a system also has profound implications for quantum information processing, serving as a long-term memory that can store the full q...

We numerically and experimentally demonstrate efficient light couplers between topological slow light waveguides in valley photonic crystals (VPhCs) and wire waveguides. By numerical simulations, we obtained a high coupling efficiency of -0.84 dB/coupler on average in the slow light regime of a group index ng = 10 - 30. Experimentally, we fabricated the couplers in a Si slab and measured the transmitted power of the devices. We realized a high coupling efficiency of approxima...

We present slow-light photonic crystal waveguide designs that provide a $\times$8.6 improvement of the local density of optical states at a fully chiral point over previous designs.

We experimentally demonstrate topological slow light waveguides in valley photonic crystals (VPhCs). We employed a bearded interface formed between two topologically-distinct VPhCs patterned in an air-bridged silicon slab. The interface supports both topological and non-topological slow light modes below the light line. By means of optical microscopy, we observed light propagation in the topological mode in the slow light regime with a group index $n_{\rm g}$ over $30$. Furth...

We present a method to control the resonant coupling interaction in a coupled-cavity photonic crystal molecule by using a local and reversible photochromic tuning technique. We demonstrate the ability to tune both a two-cavity and a three-cavity photonic crystal molecule through the resonance condition by selectively tuning the individual cavities. Using this technique, we can quantitatively determine important parameters of the coupled-cavity system such as the photon tunnel...

We have demonstrated what we believe to be the first waveguide photonic crystal cavity operating in the mid-infrared. The devices were fabricated from Ge23Sb7S70 chalcogenide glass on CaF2 substrates by combing photolithographic patterning and focus ion beam milling. The waveguide-coupled cavities were characterized using a fiber end fire coupling method at 5.2 {\mu}m wavelength, and a loaded quality factor of ~ 2,000 was measured near the critical coupling regime.

We have measured the photonic bandgap in the transmission of microwaves through a two-dimensional photonic crystal slab. The structure was constructed by cementing acrylic rods in a hexagonal closed-packed array to form rectangular stacks. We find a bandgap centered at approximately 11 GHz, whose depth, width and center frequency vary with the number of layers in the slab, angle of incidence and microwave polarization.

Atomically-thin black phosphorus (BP) is an emerging two dimensional (2D) material exhibiting bright photoluminescence in the near infrared. Coupling its radiation to photonic nanostructures will be an important step toward the realization of 2D material based nanophotonic devices that operate efficiently in the near infrared, which includes the technologically important optical telecommunication wavelength bands. In this letter, we demonstrate the optical coupling between at...

Chip-scale multimode optomechanical systems have unique benefits for sensing, metrology and quantum technologies relative to their single-mode counterparts. Slot-mode optomechanical crystals enable sideband resolution and large optomechanical couplings of a single optical cavity to two microwave-frequency mechanical modes. Still, previous implementations have been limited to nanobeam geometries, whose effective quantum cooperativity at ultralow temperatures is limited by thei...