DEFENCE OF THE DOCTORAL DISSERTATION BY ABDUR REHMAN ANWAR

Defence of the Doctoral Dissertation by Abdur Rehman Anwar

IPS invites you to the Defence of the Doctoral Dissertation by Abdur Rehman Anwar titled: Edible optical microcavities and microlasers. The defence will take place on Monday, 20 July 2026, at 12:00 p.m. at the IPS Lecture Room (N205-N206, Jamova c. 39, 1000 Ljubljana). You can also join the defence via the following link: Zoom, Meeting ID: 812 6520 4218, Passcode: 009235.

Supervisor: Assoc. Prof. Matjaž Humar.

Short summary:

Food fraud and contamination are growing global concerns. Current barcodes and sensors are printed on packaging–meaning they can be removed, tampered with, or fail to reflect what is actually inside the product. This thesis asks a simple but novel question: what if the barcode or sensor could be placed directly inside the food itself?

To answer this, we developed the first lasers made entirely from edible materials, using chlorophyll extracted from spinach leaves and vitamin B2 as light-emitting components incorporated into microscopic optical cavities. Two designs were demonstrated–droplet-based cavities and mirror-based linear cavities–both producing extremely narrow optical emission peaks that serve as unique fingerprints.

These edible microlasers were embedded directly into food products including compote, honey, and olive oil, functioning as optical barcodes capable of encoding manufacturer identity and expiration dates. Their inherent microscopic size variations make them impossible to counterfeit. The same microcavities also acted as sensors, monitoring sugar concentration, pH, bacterial growth, and temperature exposure in real time inside sealed containers.

All materials are completely safe for consumption, do not affect taste or appearance, and are biodegradable. The concepts extend beyond food to pharmaceuticals, cosmetics, and agriculture–wherever secure, in-product authentication and quality monitoring are needed.

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