Can you imagine the electronic or photonic devices without Silicon (Si) or the derivative of Si? “Yes”, suggests the latest breakthrough research on micro-organic photonic integrated circuits/devices (OPICs) using flexible organic crystals as basic optical components by researchers from the School of Chemistry at the University of Hyderabad (UoH).

The 20th century has witnessed numerous revolutionary inventions that resulted in the luxurious lifestyle of humans. However, the discoveries and developments like computers and electronic data communication systems have changed the course of the human thought process. As the ease of access to modern technology increased, the cost of electronic systems came down drastically, resulting in faster data generation and transfer. The present-day electronic-based-data communication system is inefficient as most of the energy is spent on the charging and discharging wires rather than for logic. Researchers thought of a light-based data transfer technique as a potential alternative to overcome these demerits and achieve energy-efficient data processing technology. Early research activities focused on developing silicon-based photonic integrated circuits (PICs). These devices are capable of transferring/processing information using light, primarily due to the viable and cost-effective manufacturing industry. The recent trend in PIC research has witnessed the enormous venture in developing quantum computing-based technologies for data processing.

In this context, Mr. Jada Ravi, the final year PhD student in the group of Prof. R. Chandrasekar, School of Chemistry, has exploited flexible organic crystal waveguides as a substitute to silicon-based waveguides to built organic PICs (OPICs). The PICs fabricated using organic crystals/materials are called OPICs. Here two things are essential, the material and the fabrication technique. The vast knowledge of synthetic organic chemistry allows for novel design, synthesis, and processing of organic crystals depending on the desired property (mechanical or optical). Hence, it will enable us to develop flexible organic waveguides with ease. Recent developments in flexible waveguides prove the versatility of organic crystals as effective light transducers. This impeccable mechanical flexibility of crystal waveguides makes them superior candidates for OPICs fabrication. However, the crystals cannot be transformed into PICs using conventional techniques. Organic crystals being low melting, high thermal conditions, traditional PIC fabrication techniques cannot be employed. Therefore, Prof. R. Chandrasekar’s group envisioned the mechanophotonics approach (a field developed by his research group) to micromanipulate organic crystal waveguides and resonators using a confocal optical microscope attached to atomic force microscopy (AFM) cantilever tip. The remarkable micron-sized sensitivity offered by this technique enables the construction of complex OPICs, as shown in the artistic diagram [NDIPH and BPEA correspond to different colour emitting crystals].

The UoH team successfully demonstrated the construction of functional OPIC, which deliver excitation-position-dependent mechanism-selective light outputs at various crystal termini. The uniqueness of the fabricated circuit is all the essential optical elements (waveguide and ring resonator) are obtained from flexible organic crystals. A clever design strategy to exploit the energy transfer mechanism from one crystal to another cemented the signal bandwidth specificity adding to its performance. Further, due to crystal flexibility, the OPICs are reconfigurable depending upon technological necessity. The mechanical compliance of the flexible crystals was utilized to achieve multiple circuits by post-fabrication modification, which is not possible with silicon-based PICs. Hence, this work opens a new dimension towards the development of all-organic PICs. The researchers believe this field’s advancement takes them closer to achieving light-based communication technologies with low-cost devices.

Mr. Jada Ravi (Left) along with Prof. R. Chandrasekar

Mr. Jada Ravi is the first author of the two back-to-back research articles published in the prestigious Advanced Functional Materials (JIF: 18.808] journal of Wiley-VCH, Germany. It is a Nature-indexed journal.

  1. “Geometrically-Reconfigurable, Two Dimensional, All-Organic Photonic Integrated Circuits Made from Two Mechanically and Optically Dissimilar Crystals” Funct. Mater.(2021), DOI;
  2. Mechanically Reconfigurable Organic Photonic Integrated Circuits Made from Two Electronically Different Flexible Microcrystals” Funct. Mater.(2021), 31, 2100642.