Membranes made from silicon nitride have significantly higher mechanical Q-factors under tensile stress than those made of other dielectric materials. This makes them ideal candidates for membrane reflectors that provide high finesse in Fabry-Perot cavities or membrane-in-the-middle optomechanical systems. Building on our previous work with one-dimensional gratings on suspended membranes, we patterned two-dimensional photonic crystal gratings on monolithic, suspended membranes made from silicon nitride. These high-Q membranes exhibited high reflectivity, upwards of 99%, over several nanometers in the telecom band. To probe their optical response in a cavity environment, we used these membrane reflectors as the moving mirror in a Fabry-Perot cavity. We were able to realize cavities with a finesse of over 4,500.
We report a novel bi-layer photonic crystal slab (PCS) Fano modulator via a coupled double-layer Si nanomembrane (SiNM) capacitor like structure. Surface normal incident light intensity modulation near 1500nm was achieved by carrier accumulation induced resonance spectral shifting. Device performance simulation suggests the opportunity for high speed modulation exceeding GHz with 20μm × 20μm device size.
We present here the design of a robust broadband high efficiency surface-normal vertical to in-plane optical coupler using fourth-order gratings. The fourth-order gratings can be designed such that the zero-order diffraction is suppressed while the diffraction efficiencies of the higher orders are enhanced for the in-plane coupling. We numerically demonstrated the surface normal incidence light coupling efficiency of 88.5% at 1,535 nm with a 3 dB bandwidth of 42 nm and 1dB bandwidth of 28 nm. Large fabrication tolerance of the fourth-order grating is also assessed.
Based on Fano resonance principles in photonic crystals, high performance broadband reflectors can be realized with 100% reflection. Applying an innovative magnetic field guided metal-assisted chemical etching (MacEtch) process, we report here high performance membrane reflectors on SOI with controlled sidewall etching and high reflection around 1550 nm. This work represents the first demonstration of magnetically guided MacEtch (<i>h</i>-MacEtch) of periodic arrays of discrete nanoholes of sub-micron dimensions. Such an innovative process can lead to facile formation of large area 2D and 3D nanoscale-structures, for high performance photonic crystal membrane reflectors, filters, and metamaterials.
We report here modified absorption property of InGaAs nano-membrane on a Fano filter made of patterned single
crystalline silicon nano-membrane transferred onto glass substrate. Placement of an ultra-thin InGaAs film on Si Fano
resonant membrane enhances the absorption with simulated enhancement factor ~35 and measured enhancement factor
of ~26. Leaky modes in the photonic crystal (PC) consist of high field standing waves that can be coupled to the out of
plane radiation mode provided by lattice matching of the PC. We will present simulation, device fabrication and
experimental characterization of stacked ultra-thin InGaAs/Si Fano resonance membrane in the IR regime.
Photon recycling effect has significant influence on the extraction efficiency of LEDs, which
active regions possess high spontaneous emission efficiency, i.e. high material quality. Therefore,
the conventional definition of internal quantum efficiency should be revised as pointed out by other
researchers. In this work, some more detailed considerations of photon extraction efficiency in
LEDs are examined using a simple slab structure. Theoretical modeling results show that in order
to improve the overall light conversion efficiency, it is necessary to remove the device substrate, to
optimize the overall doping profile design, and to use highly reflective metal contacts or DBR