Light Fidelity, or Li-Fi, an optical wireless technology, has opened new avenues for strengthening military communications in the contested electromagnetic spectrum. India’s strengths include a mature communications architecture, a capable industry, a broad research base, standards, and a proven route from innovation to procurement. The opportunity is to align these behind a shared objective, with clear ownership across the services, DRDO, industry and the Department of Telecommunications.

Light Fidelity, or Li-Fi, an optical wireless technology, has opened new avenues for strengthening military communications in the contested electromagnetic spectrum. A Delhi-based firm reported in March 2026 that it has secured a contract to deploy free-space optical links across Indian submarines.[1] The company is backed by three grants from the Ministry of Defence’s Innovations for Defence Excellence (iDEX) programme.[2] An optical link needs no spectrum allocation or host-nation clearance, since light sits above 3,000 GHz, outside the International Telecommunication Union (ITU) Radio Regulations.[3] A link confined to an optical beam is also harder to locate, jam or intercept from outside it.

The brief seeks to understand LiFi adoption in the military domain. It argues that India needs to align its various building blocks, such as a Centre of Excellence (CoE) on Li-Fi,[4] a Defence Research and Development Organisation (DRDO) development line,[5] the IDEX pipeline, and a capable defence-electronics industry. Optical wireless, an instrument of spectrum survivability for fixed nodes, can complement the fibre backbones India has built.

The Spectrum as Contested Ground

Modern operations depend partly on control of the electromagnetic spectrum. Every emission can be detected, located and targeted, and a receiver holds a range advantage over the transmitter it listens to. A fixed headquarters carries several emitters; each of them becomes a detection opportunity.[6] Reducing that signature without losing connectivity is the problem that is addressed by optical wireless communication. Li-Fi and free-space optics are spectrum-survivability tools for nodes that cannot move. Emission control—managing one’s own emissions to lower the probability of detection—is a recognised discipline.

The war in Ukraine has shown electronic warfare shaping targeting in real time. Operation Sindoor was fought across a sensor-rich environment in which India’s air-defence and counter-drone systems performed significantly, with the Air Force Network serving as the backbone of the Integrated Air Command and Control System (IACCS).[7]The network delivers decision advantage and also concentrates emissions at command nodes. However, for survivability, protecting their signature is important.

The concept of sending data via light dates back to Alexander Graham Bell, who transmitted speech via a sunbeam with his 1880 photophone. The effort was only defeated by unreliable sunlight and crude receivers.[8] The deficiencies of the photophone were overcome by light-emitting diodes (LEDs) and photodiodes—an LED can be switched millions of times a second, and a photodiode reads the flicker back into data. The main motive behind the concept is the scarcity of the radio spectrum, which is finite and congested, while the light band above it is a thousand times wider and unlicensed.[9]

Professor Harald Haas of the University of Edinburgh coined the term ‘Li-Fi’ and earned the label ‘father of Li-Fi’.[10] He gave a Technology, Entertainment Design (TED) talk, ‘Wireless Data from Every Bulb’ in 2011, about streaming data from an ordinary LED. Two years before this TED talk, in 2009, Germany’s Fraunhofer Institute demonstrated the feasibility of underlying visible light communication at 125 Mbit/s over a distance of five metres.[11]

Li-Fi needs near line of sight, with a range of about 10 metres.[12] The academic literature confirms line-of-sight dependency and optical attenuation as the binding limits for Li-Fi.[13] Free-Space Optics (FSO) is generally used for long-range applications and operates with a beam between two fixed points over distances of up to kilometres. This explains why the ITU groups it with Li-Fi under optical wireless communication (OWC).[14]

Li-Fi and Electronic Warfare

There are three aspects of electronic warfare and optical wireless communication.[15] The first is electronic support: intercepting and locating emissions. A link confined to a beam offers little to a distant receiver; the same is the concept behind the United States Army’s ‘zero-radio-frequency footprint’ operations centre.[16] It is harder to intercept the beam from outside if it is not invisible: light leaks through windows, and a sensor inside the cone can detect it.

Second is electronic attack: an optical link cannot be jammed by a distant radio emitter, though a beam can be dazzled by bright light or degraded by smoke and dust. This means it requires an adversary to be close by only to cause a local effect. Third is electronic protection: the surest protection is not emitting on contested frequencies at all. Emission control is a form of........

© IDSA