Glowing liquid crystals bending light

Light Switch of the Future: How Lasers Are Being Revolutionized

Elliot Brynn in Tech & Innovation September 2025 • 4 min read.

"Scientists have discovered a way to control random lasers with near-infrared light, paving the way for faster and more energy-efficient optical devices."

Lasers have transformed many areas of our lives, from reading barcodes at the grocery store to performing delicate surgeries. Now, a new type of laser, called a random laser, is emerging with the potential to revolutionize technology further. Unlike conventional lasers that rely on mirrors to create a coherent beam of light, random lasers generate light through multiple scattering in a disordered medium. This unique property makes them promising for various applications, including advanced displays, medical imaging, and optical sensing.

However, controlling random lasers has been a challenge. Traditional methods often involve complex setups or external stimuli. Recently, scientists have made a significant leap forward by demonstrating a novel way to control random lasers using near-infrared light. This breakthrough could pave the way for more efficient and versatile optical devices.

In a recent study published in the IEEE Photonics Journal, researchers from Tampere University of Technology in Finland and the University "Roma Tre" in Italy, report an all-optical method to modulate and switch light-guided random laser emission, using optically pumped dye-doped nematic liquid crystals. By using a continuous-wave near-infrared beam, the researchers were able to form a reorientational spatial soliton, and affect the laser emission.

How Does Near-Infrared Light Control Random Lasers?

The researchers used a special type of material called nematic liquid crystals (NLCs), which are similar to those found in LCD screens. These crystals have the ability to align in a specific direction, which affects how light passes through them. The NLCs were also doped with a dye that emits light when stimulated by a green pump laser.

Here's the simple breakdown:

Green Pump Laser: Provides the energy to stimulate the dye molecules in the NLCs, causing them to emit light.
Near-Infrared Beam: A separate beam of near-infrared light is directed into the NLCs alongside the pump laser. This beam is non-resonant, meaning it doesn't directly interact with the dye molecules. Instead, it interacts with the NLCs themselves.
Spatial Soliton Formation: The near-infrared beam causes the NLC molecules to reorient, creating a channel or waveguide for the light. This channel is called a spatial soliton.
Light Confinement and Amplification: The spatial soliton acts like a tiny optical fiber, confining the light emitted by the dye molecules and guiding it through the material. This confinement amplifies the light, resulting in a brighter and more directional laser emission.
Switching and Modulation: By controlling the intensity of the near-infrared beam, the researchers can turn the random laser on or off, or even modulate its output. A weak near-infrared input can achieve energy amplifications of laser emission.

The whole process leverages the optical properties of nematic liquid crystals, combined with the unique characteristics of random lasing, to achieve precise control over light emission.

The Future of Lasers Is Bright

This new method of controlling random lasers with near-infrared light opens up a new realm of possibilities for optical technology. With their ability to be easily manipulated and controlled, random lasers may soon find applications in various areas, from high-resolution displays and advanced medical imaging to more efficient optical communication networks.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1109/jphot.2018.2870739, Alternate LINK

Title: Near-Infrared Switching Of Light-Guided Random Laser

Subject: Electrical and Electronic Engineering

Journal: IEEE Photonics Journal

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Authors: Sreekanth Perumbilavil, Martti Kauranen, Gaetano Assanto

Published: 2018-10-01

Everything You Need To Know

What are random lasers, and how do they differ from conventional lasers?

Random lasers are a type of laser that generates light through multiple scattering in a disordered medium, unlike conventional lasers that rely on mirrors to create a coherent beam. This unique property makes random lasers promising for applications such as advanced displays, medical imaging, and optical sensing. The absence of mirrors simplifies their design and opens doors to creating lasers in unconventional shapes and materials. However, controlling the light emission from random lasers has traditionally been more challenging than controlling conventional lasers, a challenge addressed by the use of near-infrared light.

How does near-infrared light enable the control of random lasers, and what materials are involved?

Near-infrared light controls random lasers by interacting with nematic liquid crystals (NLCs) doped with a dye. A green pump laser stimulates the dye molecules to emit light. A separate near-infrared beam then causes the NLC molecules to reorient, forming a spatial soliton. This spatial soliton acts as a waveguide, confining and amplifying the light emitted by the dye molecules, allowing for switching and modulation of the laser output. The intensity of the near-infrared beam determines whether the random laser is on or off, enabling precise control.

What are spatial solitons, and what role do they play in controlling random lasers with near-infrared light?

Spatial solitons are channels or waveguides formed when a near-infrared beam causes nematic liquid crystal (NLC) molecules to reorient. These solitons act like tiny optical fibers, confining the light emitted by the dye molecules within the NLCs and guiding it through the material. This confinement amplifies the light, resulting in a brighter and more directional laser emission. By controlling the intensity of the near-infrared beam, researchers can manipulate the spatial soliton, thereby controlling the random laser's output.

What potential applications could emerge from controlling random lasers with near-infrared light, and how might these impact existing technologies?

The ability to control random lasers with near-infrared light opens up possibilities for applications in high-resolution displays, advanced medical imaging, and more efficient optical communication networks. In displays, random lasers could enable brighter, more energy-efficient screens. For medical imaging, their unique properties could lead to new diagnostic techniques. In optical communication, they could enhance the speed and efficiency of data transmission. The development is a shift from existing devices which might be larger, consume more power or need more complex systems to achieve similar output.

What are nematic liquid crystals (NLCs) and why are they crucial in the development for controlling random lasers with near-infrared light?

Nematic liquid crystals (NLCs) are a special type of material similar to those found in LCD screens. Their unique property of aligning in a specific direction, which affects how light passes through them, is crucial. In the context of controlling random lasers, NLCs are doped with a dye that emits light when stimulated by a green pump laser. The near-infrared beam interacts with the NLCs, causing them to reorient and form a spatial soliton, which then guides and amplifies the light. Without the reorientational properties of NLCs, the creation and manipulation of spatial solitons, and thus the precise control of random laser emission, would not be possible.