New technology developed to transport radio frequency (RF) through optical methods could improve digital & satellite communication.

New Delhi: A groundbreaking advancement in the field of Next-Generation Photonic Analog-to-Digital Converters (NG-PADC) has been achieved through the creation of innovative prototypes. These prototypes are capable of instantly measuring, generating, and transmitting Radio Frequency (RF) through optical means. This breakthrough has the potential to bring about transformative changes across various sectors, including rapid digital communication, enhanced satellite communication, improved medical imaging, and more efficient Photonic radars.

Analog-to-digital converters (ADCs) play a pivotal role in advancing modern digital receivers. However, electronic ADCs (EADCs) face limitations, especially in terms of vertical resolution at high bandwidths. To address this issue, the NG-PADC project explores two Photonics-based solutions.

The first approach involves modulating RF onto an optically rich pulsed source, which is then stretched in the optical domain using a dispersive medium. This effectively transforms high-frequency RF signals into lower-frequency signals, significantly reducing the input bandwidth requirements for the subsequent ADC. The optical clock, generated by a short pulsed laser, constitutes the second approach. Optical clocks exhibit fewer timing fluctuations (timing jitter) compared to electronic clocks. By sampling high bandwidth RF signals with stable optical clocks, a substantially higher effective number of bits (ENOB) can be achieved compared to using electronic clocks. This novel approach results in a time-stretched photonic ADC with a 12-fold higher effective bandwidth than traditional EADCs, facilitating the digitization of signals with greater precision.

The NG-PADC, developed by IIT Madras with support from the IMPRINT program of the Science and Engineering Research Board (SERB), integrates a time-stretched photonic ADC with a remarkably superior effective bandwidth compared to conventional EADCs. This enables the sampling of higher bandwidth signals using lower bandwidth EADCs.

The research team’s collaboration with the Defense Research and Development Organization (DRDO) and an industry partner revealed the potential of these solutions, as radar signal processing also encounters limitations due to existing electronics. Leveraging these insights and expertise, the NG-PADC was conceived.

The scientists behind this breakthrough have joined forces with Lightmotif Automation, a company based in Hyderabad, to facilitate the dissemination of this technology to a wider audience.