Optically Pumped Polaritons: Enabling Perovskite LEDs with Coherent Light States

Light-emitting diodes (LEDs) have had quite an impact on modern technology, powering everything from smartphone displays to large-scale lighting. Yet, there is one thing LEDs cannot do easily and that's produce coherent light states. LED emission is broad and uncoordinated, as the light waves are not aligned in phase, so they spread in many directions and cannot form a sharp, focused beam. Lasers, in contrast, emit narrow and coherent beams but require a process called population inversion, which is energy demanding and harder to integrate into compact devices.

Researchers are turning to optically pumped perovskite LEDS as a promising way to produce coherent light without population inversion. Their operation depends on optically pumped polaritons, hybrid particles formed when light and matter strongly couple inside a microcavity. Optically pumped polaritons enable perovskite LEDs to combine the efficiency of traditional LEDs with the coherence of lasers, an effect that researchers examine using microspectrophotometry.

What are optically pumped polaritons?

Optically pumped polaritons appear when excitons, which are bound pairs of electrons and holes, strongly couple with photons inside an optical cavity. Instead of existing as separate entities, excitons and photons merge into new states called polaritons. These polaritons carry traits from both sides:

• From photons: they gain very low effective mass, allowing them to move easily.
• From excitons: they acquire the ability to interact and scatter.

Such an unusual combination enables polaritons to display collective quantum effects, and under the right conditions they can all occupy the same state, producing coherent light states that resemble laser emission.

The role of optically pumped polaritons in perovskite LEDs

Conventional perovskite LEDs emit light that is bright but incoherent. To reach coherence, researchers use optically pumped polaritons. These hybrid states allow perovskite microcavities to sustain strong coupling and condensation, forming coherent light states within a device structure that otherwise behaves like an LED.

As a mechanism for coherence, optically pumped polaritons do more than act as a proof of principle. They actively enable perovskite LEDs to move beyond spontaneous emission and into the regime of coherent emission. By showing that perovskite LEDs can host polariton condensation, they provide the physical mechanism for combining the efficiency of LEDS with the coherence of lasers.

How optically pumped polaritons enable coherent light states in perovskite LEDs

Optically pumped polaritons transform how perovskite LEDs behave, allowing them to emit coherent light without relying on population inversion. The sequence from excitation to emission goes as follows:

• Exciton generation - The process begins inside a perovskite LED, where a pump laser excites the material and generates electron-hole pairs called excitons.
• Polariton formation - These excitons then couple strongly with photons in the microcavity, producing optically pumped polaritons.
• Condensation - When the polaritons build up, they relax into the lowest energy state. This collective process, known as condensation, is what enables coherence without population inversion.
• Coherent emission - Once condensation occurs, the perovskite LED emits light that is spectrally narrow and phase aligned, forming coherent light states.

This sequence shows that coherence in perovskite LEDs does not arise from population inversion but from the collective behavior of polaritons. Because condensation occurs at relatively low excitation thresholds, it provides a practical route to coherent emission in perovskites and other materials, like organic semiconductors, that are otherwise limited to spontaneous, incoherent light. Such a distinction is what makes optically pumped polaritons a central mechanism for advancing perovskite-based coherent light sources.

Potential Applications for perovskite LEDs with coherent light states

Perovskite LEDs that generate coherent light states open new possibilities across both consumer and industrial technologies. Their combination of efficiency, compact size, and coherence makes them suitable for:

• High-resolution displays and holography - enabling sharper images, richer colors, and more realistic 3D projections.
• On-chip light sources - offering integrable coherent emitters for photonic circuits and lab-on-chip devices.
• Augmented and virtual reality - supporting lightweight, low-power projectors that improve image quality in wearable systems.
• LiDAR and precision sensing - enhancing spatial resolution and detection accuracy for navigation, robotics, and industrial metrology.

By providing coherent light in an LED platform, perovskite devices extend far beyond conventional lighting and display roles, positioning themselves as versatile tools for next-generation photonics.

Using microspectrophotometry to study optically pumped polaritons

Examining optically pumped polaritons in perovskite LEDs requires a method that can capture the subtle features of how light and matter interact. Microspectrophotometry offers the capability to measure light from regions smaller than a micron. This level of precision is especially important for the perovskite layers within LEDs, which often show variations across their surface that can impact optical performance.

With microspectrophotometry, scientists can:

• See anticrossing and Rabi splitting, clear signs of strong exciton-photon coupling
• Detect threshold behavior as emission intensity rises during condensation
• Measure linewidth narrowing and blueshift that signal coherent polariton emission
• Link optical output to structural features through spatial mapping.

These measurements build a detailed picture of polariton behavior and confirm that coherent light states in perovskite LEDs originate from polariton condensation.

Enabling coherent PeLEDs with optical pumping and precision measurement

Optically pumped polaritons provide the mechanism that allows perovskite LEDs to move beyond spontaneous emission and generate phase-aligned light states. Microspectrophotometry is crucial for examining the strong coupling and condensation processes that give rise to coherent light in perovskite LEDs. At CRAIC Technologies, we provide advanced microspectroscopy tools such as the 2030PV PRO™ Microspectrometer. Such instruments deliver the precision researchers need to study polariton behavior at the microscale and to take the next step from laboratory demonstrations to fully coherent, practical perovskite LEDs. Contact us now to learn more about how our microspectroscopy solutions can support your research into polaritons and the development of advanced perovskite LEDs.

References

1. Dini K, Hu Z, Leng M, et al. Optically Pumped Polaritons in Perovskite Light-Emitting Diodes. ACS Photonics. 2023;10(5):1349-1355. doi:10.1021/acsphotonics.2c01999.
2. Cao X, Di D, Lian Y, et al. Continuous-wave perovskite polariton lasers. Science Advances. 2025;11(2). doi:10.1126/sciadv.adr8826.