Micromechanical Fabrication of Resonator Waveguides Integrated Four‐Port Photonic Circuit from Flexible Organic Single Crystals

Abstract

By using a mechanophotonics approach, three flexible organic microcrystals of (E)‐1‐(4‐(dimethylamino)‐phenyl)iminomethyl‐2‐hydroxyl‐naphthalene (DPIN) are micromanipulated, and dual‐waveguides coupled ring resonator is fabricated. The flexibility of the DPIN crystal arises owing to its spring‐like expansion and contraction of π∙∙∙π stacked molecular chains along the (002) plane. The crystals also act as optical waveguides in straight and bent geometries with very low optical loss coefficients. The fluorescence (FL) spectra of the guided light also display Fabry‐Pérot modes. Precise mechanical manipulation of microcrystals with atomic force microscopy cantilever tip bent a straight crystal waveguide to 360° angle forming a ring‐shaped crystal resonator (diameter ≈58.6 µm). The positioning and integration of two straight parallelly oriented waveguiding crystals (bus and drop) along the opposite edge of the ring resonator forms the first of its kind all‐organic crystal‐based dual‐waveguides coupled ring resonator. The fabricated circuit with four ports selectively guides the produced input FL to through and drop ports via active, passive waveguiding and FL reabsorbance mechanisms.

Geometrically Reconfigurable, 2D, All‐Organic Photonic Integrated Circuits Made from Two Mechanically and Optically Dissimilar Crystals

“…The development of techniques for processing micrometersized molecular crystals is central to the realization of a miniature OPIC technology. However, the mechanophotonic [11][12][13][14][15][16] properties of flexible micro-sized crystals (<50 μm) on a substrate have not been explored well in the past due to the dearth of suitable techniques for crystal processing. Recently, atomic force microscopy (AFM), was suggested as an ideal technique for precise microcrystal processing.…”

“…Recently, atomic force microscopy (AFM), was suggested as an ideal technique for precise microcrystal processing. [11][12][13][14][15][16]20] These studies concluded that some of the drawbacks of silicon-based photonics could be potentially overcome by using suitable plastic crystals where the mechanical deformation does not alleviate the optical performance. The ease of fabrication by using this approach of OPICs with exceptional or strongly curved morphologies such as optical waveguides [11][12][13][14][15][16][20][21][22][23] bent at a right angle, or ring resonators or cavities [24] would allow for complete control over the light propagation in two dimensions.…”

“…[11][12][13][14][15][16]20] These studies concluded that some of the drawbacks of silicon-based photonics could be potentially overcome by using suitable plastic crystals where the mechanical deformation does not alleviate the optical performance. The ease of fabrication by using this approach of OPICs with exceptional or strongly curved morphologies such as optical waveguides [11][12][13][14][15][16][20][21][22][23] bent at a right angle, or ring resonators or cavities [24] would allow for complete control over the light propagation in two dimensions. Furthermore, unlike high-index and non-absorbing photonic circuits, a combination of such active-type plastic crystal ring resonators and optical waveguides could enable control over the photoluminescent light propagation direction due to clockwise and anticlockwise light-routing operation by the resonators.…”

“…Flexible molecular crystals are evolving as attractive alternative materials for PICs whose potential has only been recognized recently. [11][12][13][14][15][16] The flexible molecular crystals are categorized into two types: [17] elastic crystals, which are capable of spontaneous reversion of their shape after being deformed, and plastic crystals, which undergo permanent stress-induced deformation. The elastic crystals are thought to be able to deform by the expansion of the distance between their molecules on the outer (convex) side and contraction of those on their inward (concave) side of the kink of the bent crystal relative to their equilibrium position before the deformation.…”

“…The combination of flexibility and favorable optical attributes in some of these materials appears to be suitable for fabrication of organic PICs (OPICs). [11][12][13][14][15][16]…”