Advanced All‐Organic Microphotonic Components and Integrated Circuits
Rajadurai Chandrasekar
Abstract
Organic crystals are potential challengers to traditional photonic materials such as silicon, silicon nitride, and main group elements. The reason for making such an impudent statement is the successful demonstration of several organic crystal-based photonic microcomponents viz. optical waveguides (active[1] and passive[2]), flexible optical waveguides (active[3] and passive[4]), cavities (active[5] and passive[6]), modulators,[7] and lasers[8] over the last decade and a half. The ultimate goal is the precise integration of these tiny crystal photonic modules on a silica substrate to fabricate functional microcircuits; though the task is considered difficult. Nevertheless, the invention of atomic force microscopy cantilever tip-based mechanical operations (lifting, cutting, bending, slicing, moving, aligning and integrating) at the University of Hyderabad aids the micromanipulation of microcrystal photonic components with precision – the so-called Mechanophotonics technique.[9, 10] The same technique has paved the way to effectively construct various photonic microscale elements viz. bent waveguides,[11] ring resonators,[12] directional couplers,[13] multiplexers,[14] and prototype organic crystal photonic integrated circuits.[15, 16] It is expected that the industrial-scale manufacturing of organic crystal photonic components of various geometrical shapes with high precision and reproducibility will ensue with the development of advanced processing techniques.[17, 18] This special section focuses on 21 contributions including 4 Reviews and 17 Research Articles related to All-Organic Microphotonic Components and Integrated Circuits by various research groups. Four articles are on multidimensional crystal waveguides, waveguides that operate at low temperatures (article numbers 2203087, 2200627, 2201810) and thermos-responsive nanofibers (2202056). Three articles cover the importance of heterostructures grown by molecular epitaxy in waveguides and junctions (article numbers 2200776, 2201000, and 2200852). The utilization of light-emitting transistors (article number 2201644), directional and light-extracting light-emitting diodes (article numbers 2200877, 2202557), photodetectors (2202823), and optical gates (article number 2202563) are other important additions to the collection. To power all-organic circuits, organic lasers are important; four papers elaborate on the advances made in microcrystal lasers and their arrays (article numbers 2200815, 2202797, 2200872, 2202879). Non-linear optical (NLO) organic circuits are one of the promising areas yet to be realized. In this context, two articles present crystalline materials which emit THz waves (article number 2201420) and NLO-cavities displaying electrostriction phenomenon (article number 2201635). Finally, the integration of organic crystal photonic components in a single chip is the holy grail. Towards this goal, three articles focus on the mechanophotonics of several flexible single crystal waveguides and subsequent construction of optical interferometers (article number 2201009), race track type resonators (article number 2201507), and monolithic and hybrid micro-circuits (article number 2201518). Finally, it has been a great pleasure and honor to edit this special section. We thank all authors for their outstanding contributions. I am very grateful to Dr. Nadezda Panarina and the team of Advanced Optical Materials for their valuable support in preparing this special section. The authors declare no conflict of interest. Rajadurai Chandrasekar is a Professor at the School of Chemistry and Centre for Nanotechnology, University of Hyderabad, India. His research contribution includes organic-optical waveguides, -passive cavities, -photochromic crystal modulators, -non-linear optical waveguides and cavities, -directional couplers, -chiral cavities, -crystal interferometry and circuits. Recently, intending to fabricate Organic Crystal Photonic Integrated Circuits, he initiated a new research field namely, Mechanophotonics, where mechanical micromanipulation technique fuses with nanophotonics of molecular microcrystals.