Multimode Interference of Bloch Surface Electromagnetic Waves

Abstract

Integrated photonics aims at on-chip controlling light in the micro-and nanoscale ranges utilizing the waveguide circuits, which include such basic elements as splitters, multiplexers, and phase shifters. Several photonic platforms, including the well-developed silicon-on-insulator and surfaceplasmon polaritons ones, operate well mostly in the IR region. However, operating in the visible region is challenging because of the drawbacks originating from absorption or sophisticated fabrication technology. Recently, a new promising all-dielectric platform based on Bloch surface electromagnetic waves (BSWs) in multilayer structures and functioning in the visible range has emerged finding a lot of applications primarily in sensing. Here, we show the effect of multimode interference (MMI) of BSWs and propose a method for implementing the advanced integrated photonic devices on the BSW platform. We determine the main parameters of MMI effect and demonstrate the operation of Mach−Zehnder interferometers with a predefined phase shift proving the principle of MMI BSW-based photonics in the visible spectrum. Our research will be useful for further developing a versatile toolbox of the BSW platform devices which can be essential in integrated photonics, lab-on-chip, and sensing applications.

Efficient Emission Outcoupling from Perovskite Lasers into Highly Directional and Long‐Propagation‐Length Bloch Surface Waves

“…Proximity of PBG leads to high BSW leakage rate (see Section S1, Supporting Information), which helps us to study the BSW propagation using leakage radiation microscopy. [ 33,34 ] BSW can be excited in a wide range of spectrum from 450 to 650 nm, where effective refractive index $$n_{\text{BSW}}$$, which is equal to the ratio of BSW propagation constant $$k_{\text{BSW}}$$ and the radiation wavevector in vacuum $$k_0$$, decreases from 1.27 to 1. The BSW electric field distribution calculated by the transfer matrix method [ 35 ] is shown in Figure 1c.…”

“…BSW is a leaky mode meaning that part of the BSW energy leaks into the substrate during propagation. Intensity of leakage radiation is proportional to the BSW near‐field intensity, [ 34 ] while the leakage emission angle $$\alpha$$ satisfies the phase‐matching condition $$n_{\text{BSW}} = n_{\text{sb}}$$sin($$\alpha$$), where $$n_{\text{sb}}$$ is the refractive index of the substrate. Leakage radiation was collected with an objective lens.…”

Centimeter‐Scale Propagation of Optical Surface Waves at Visible Wavelengths

“…The authors reported, through a rough experimental determination, an extinction coefficient smaller than 10 −2 cm −1 for the fundamental surface mode, [1] thus making optical surface waves relevant candidates for on-chip optical information transportation. Over the past 40 years, many studies have explored the possibilities offered by Bloch surface waves (BSWs), from the near-UV to mid-infrared wavelengths, [22][23][24][25][26][27][28][29][30] particularly for sensing applications. [31][32][33][34][35][36] Still, only very few works have discussed their propagation properties [37,38] and even fewer have made reports of experimentally measured propagation lengths.…”

Miniature Otto Prism Coupler for Integrated Photonics

“…The coupler size is scaled according to the size of the beam and is typically two to three beam diameters. We demonstrate the coupler for the Bloch surface wave (BSW) [8] platform that is all-dielectric counterpart to SPP one, but has the advantages of long propagation length [34] and ultrawide spectral range of operation (from UV [35] to mid-IR [36] ), making BSW applicable for integrated photonics, [10,[37][38][39] sensing, [40][41][42] and other fields. [43][44][45][46][47][48][49] Microprism couplers are printed on the surface of a photonic crystal using two-photon laser lithography [50] (TPL) capable of creating efficient in-plane [17] and out-of-plane microcouplers [19][20][21] operating on the mode-field matching principle.…”