Mechanical Processing of Naturally Bent Organic Crystalline Microoptical Waveguides and Junctions

Abstract

Precise mechanical processing of optical microcrystals involves complex microscale operations viz. moving, bending, lifting, and cutting of crystals. Some of these mechanical operations can be implemented by applying mechanical force at specific points of the crystal to fabricate advanced crystalline optical junctions. Mechanically compliant flexible optical crystals are ideal candidates for the designing of such microoptical junctions. A vapor‐phase growth of naturally bent optical waveguiding crystals of 1,4‐bis(2‐cyanophenylethynyl)benzene (1) on a surface forming different optical junctions is presented. In the solid‐state, molecule 1 interacts with its neighbors via CH⋅⋅⋅N hydrogen bonding and π–π stacking. The microcrystals deposited at a glass surface exhibit moderate flexibility due to substantial surface adherence energy. The obtained network crystals also display mechanical compliance when cut precisely with sharp atomic force microscope cantilever tip, making them ideal candidates for building innovative T‐ and Δ‐shaped optical junctions with multiple outputs. The presented micromechanical processing technique can also be effectively used as a tool to fabricate single‐crystal integrated photonic devices and circuits on suitable substrates.

Mechanophotonics—Mechanical Micromanipulation of Single‐Crystals toward Organic Photonic Integrated Circuits

“…Recently, we have reported a rare form of naturally bent crystals of 1,4‐bis(2‐cyanophenylethynyl)benzene (7) obtained via the vapor‐phase growth technique ( Figure A, inset). [ 24 ] The FESEM images of three representative bent crystals showed their varying bent angles namely, 160°, 140 o , and 90° (Figure 8B). These bent rods interconnected to each other, forming optical junctions of intricate geometries resulting from two crystals’ growth in an orthogonal direction.…”

“…Atomic force microscopy (AFM), combined with a confocal microscope, is a promising micromanipulation tool for the fabrication of micro OPICs. [ 1d,2h,7d,8,23–25 ] The former is a force‐based technique that uses a cantilever with or without the tip to manipulate nano/microscale crystals deposited on the surface. The latter tool gives a large field view of the sample to carryout manipulation precisely.…”

Polarised Optical Emission from Organic Anisotropic Microoptical Waveguides Grown by Ambient Pressure Vapour‐deposition

“…The micro‐optical waveguides fabricated via ambient pressure chemical vapour deposition (CVD) of π‐conjugated organic molecules have attracted increased attention due to their high chemical purity [7,22,37] . Previously, we reported the optical waveguide behaviour of self‐assembled microstructures derived from alkynyl azole and benzoazole molecules [37–44] .…”

“…The micro‐optical waveguides fabricated via ambient pressure chemical vapour deposition (CVD) of π‐conjugated organic molecules have attracted increased attention due to their high chemical purity [7,22,37] . Previously, we reported the optical waveguide behaviour of self‐assembled microstructures derived from alkynyl azole and benzoazole molecules [37–44] . The relevance of the alkynyl linker since it induces the formation of well‐ordered supramolecular structures due to their ability to form CH‐π interactions that stabilize these arrangements [45] and it is also able to induce flexibility have been demonstrated.…”

2D Metal‐Organic Complex Luminescent Crystals

“…The small α value here is competitive with those of other molecular crystal based optical waveguides [50][51][52][53][54][55][56][57][58][59][60][61] (see Table 1). From the molecule perspective, metal-organic complexes are ideal candidates to develop fluorescent optical waveguides.…”