The researchers demonstrated that a two-domain laser can perform mechanical sensing to generate microwaves and perform quantum processing

The laser is a major historical invention that has had a pervasive impact on society. The concept also has interdisciplinary applications, such as phonon lasers and atomic lasers. A laser in one physical domain can be pumped by energy in another physical domain. So far, however, all lasers demonstrated in practice have fired lasers in only one physical domain.

In a new report published in the journal Science Advances, Ning Wang and a team from the School of Optics and Photonics at the University of Central Florida in the United States and the Prysmian Group in France demonstrate the synchronization process of photon and phonon lasers. Dual-domain lasers have a variety of applications, such as optical and acoustic tweezers that perform mechanical sensing to generate microwaves and perform quantum processing. The team expects this demonstration to open up new avenues for multi-domain laser-related applications.

Development of dual domain lasers

The laser is an extension of the optical region radio-frequency electronic oscillator and the microfrequency maser. Lasers have huge applications and the concept has new extensions in various fields, such as acoustic oscillators (also known as laser oscillators) and atomic or matter wave oscillators. The concept of laser has traditionally described optical oscillators based on stimulated emission, although the terms phonon laser and atom/matter laser are also common.

In some applications, the process of emitting both photon and phonon lasers is useful. These include the development of submillimeter acoustic tweezers. The combination of ultrasound and photonic bioimaging improves imaging quality, while the two-domain laser is suitable for quantum information processing and sensing. Existing demonstrations show that Stokes optical sound waves are a by-product of phonon lasers. In this work, Wang and colleagues developed a coupled oscillator system that emits lasers in two different physical domains pumped from the same source to demonstrate how dual-domain concurrent photon and phonon lasers can enhance the output power of photon and phonon lasers.

Action principle

The team used forward stimulated Brillouin scattering to generate low-frequency curved sound waves; Interaction of photons and phonons in a two-mode fiber. Low-frequency phonons are confined to quartz fiber and have a lifetime of up to 10 milliseconds. The propagation length is about 10 meters, which also allows phonons to emit laser light. In the experimental setup, the coherent oscillation of the light waves enhances the gain of the acoustic phonons, and vice versa, resulting in laser light in both domains.

The team produced the photon and phonon laser by increasing the optical pumping power, noting four functional states of the device in which the gain of Stokes light and sound waves must exceed their loss. The experimenters devised a method that allows phonon energy within the ring cavity to promote phonon lasing. Although the phonon laser power is limited to the cavity, the Stokes optical laser can be seen at the output of the coupler.

experiment

During the experiment, the researchers used a 976 nm fiber-coupled pumping diode with a maximum output power of 400 mW. They use thermoelectric coolers to regulate the functional temperature of the system. The pump is emitted into a two-mode fiber coupled to an outer diameter ring cavity.

The scientists used a reduced cladding two-mode fiber made of pure silica cladding and a silicon dioxide core doped with germanium oxide. Since the sound field extends throughout the cladding, the process of reducing the cladding size of the dual-mode fiber improves the overlap between the sound field and the light field, thereby increasing the gain coefficient of stimulated Brillouin scattering.

Laser power

The team measured the phonon laser output power as a function of the pump power injected into the ring cavity to obtain two thresholds corresponding to the photon laser and the phonon laser. The threshold pumping power of the photon laser is 180 mW. When they increased the pumping power to 308 mW, the phonon laser also began to emit laser light.

The measured threshold pump power and output laser power are in agreement with the numerical simulation results. The photon-phonon laser represents an inverted dissipation hierarchy with a much narrower acoustic emission linewidth than the pumped laser linewidth compared to existing standards.

appearance

In this way, Ning Wang and colleagues showed how two coherently coupled lasers in different physical domains can perform a variety of practical tasks. Light and sound have different spatial and temporal properties and interact differently with materials; Therefore, their availability can be explored in different ways. This phenomenon of laser coupling in two different physical domains in the same cavity is the first research result. This achievement goes beyond existing methods, including coherently coupled lasers such as laser diode arrays.

A two-domain laser explores forward mode stimulated Brillouin scattering to achieve the coupling of concurrent photon and phonon lasers in the same cavity. Due to the lack of high-resolution and high frame rate cameras, the team did not directly observe phonon laser power in this study. The scientists observed several laser functional states associated with self-released lillouin scattering, photon lasers, and photon-phonon lasers, which are consistent with theoretical models of two-domain lasers. These results could drive future advances in photomechanics and usher in multi-domain lasers and related applications.

Source: Laser Network