New breakthrough of chip level tunable laser: finger tip size only, applicable to 404 nm ultra short wavelength

On January 4, the Lipson Nanophotonics Group from Columbia Institute of Engineering invented the world's first tunable narrow linewidth chip level laser, which can be used for visible wavelengths shorter than red (green, cyan, blue and purple). The laser means that the team has made significant progress in quantum optics for AR/VR and in the significant miniaturization of laser displays.

(Image source: official website of Lipson Nanophotonics Group)

It is reported that it is becoming more and more important to miniaturize the system into chips, but unfortunately integrated photonics has always lacked the key component to achieve full miniaturization - high-performance, chip level lasers. Although near-infrared lasers have made some progress, visible lasers used in photonic chips are still desktop sized and expensive.

It must be mentioned that lasers with emission wavelengths less than red open new possibilities for some key applications. For example, the display needs to use red, green and blue light to form any color. In quantum optics, green, blue and purple lasers are used to capture and cool atoms and ions. In underwater lidar (light detection and ranging), green or blue light is required to avoid water absorption. However, when the wavelength is less than red, the coupling and propagation loss of photonic integrated circuits increase significantly, which hinders the realization of high-performance lasers in these colors. Because of this, it is particularly critical to use tunable narrow linewidth chip level lasers to emit light of different colors.

Fingertip size high performance laser only

According to the research published in the journal Nature Photonics, researchers from the Lipson Nanophotonics Group of Columbia Institute of Engineering have invented a very pure color visible laser, whose spectral color covers from near ultraviolet to near infrared, and can be installed on fingertips. In addition, the color of the laser can be precisely adjusted, and the speed is extremely fast (up to 267 kHz per second). These advantages are crucial for applications such as quantum optics.

In the experiment, the team demonstrated for the first time chip level narrow linewidth and tunable lasers for shorter wavelengths of light than red green, cyan, blue and purple. These inexpensive lasers also have the smallest volume and shortest wavelength (404 nm) of any tunable narrow linewidth integrated laser emitting visible light.

The main author of this study, Mateus Corato Zanarella, pointed out that the exciting part of this research achievement is that they have broken the existing standards by using the power of integrated photonics. In the past, high-performance visible lasers usually require a desktop size volume and cost tens of thousands of dollars - which is obviously detrimental to their popularity.

So far, it is still difficult for researchers to realize the technology of miniaturization, large-scale deployment of tunable and narrow linewidth visible lasers. A classic example of quantum optics is that it requires the use of high-performance lasers of multiple colors in a system. The above research team expects that their findings can provide a fully integrated visible light system for existing and new technologies.

Solve coupling and propagation loss problems

By choosing Fabry Perot (FP) diode as the light source, researchers solved the problem of coupling loss, thus minimizing the impact of loss on chip level laser performance.

Different from other strategies of using different types of light sources, the team's method can achieve a record short wave (404 nm) laser, while also providing scalability of high optical power. FP laser diode is a cheap and compact solid-state laser, which can be widely used in research and industrial fields.

However, they emit several wavelengths of light at the same time and are not easy to tune, which makes them unable to be directly used in applications requiring pure and accurate lasers. By combining them with specially designed photonic chips, researchers can adjust the laser emission to a single frequency, narrow linewidth and widely adjustable form.

In addition to one platform designed by the team, it can minimize the material absorption and surface scattering loss at all visible wavelengths, thus overcoming the propagation loss problem. To guide light, they used silicon nitride, a dielectric widely used in the semiconductor industry, which is transparent to all colors of visible light.

Chris Haimberger, laser technology director of Topica Photonics, said: "As a laser manufacturer, we recognize that integrated photonics will have a huge impact on our industry and will achieve a new generation of applications that have not been achieved so far. This research achievement represents an important step towards compact, tunable visible lasers, which will provide power for the future development of computing, medicine and industry."

Future outlook: further miniaturization and large-scale deployment

It is reported that researchers have applied for temporary patents for their technology, and are currently exploring how to package lasers into independent units through optical and electrical methods, and use them as light sources for chip level visible light engines, quantum experiments and optical clocks.

Michal Lipson, professor of electrical engineering and professor of applied physics at Eugene Higgins, said: "In order to move forward, we must be able to miniaturize and scale these systems, so that they can finally be seamlessly embedded in large-scale deployment technologies. Integrated photonics is an exciting field, from optical communication to quantum information to biosensors, it is playing its subversive influence."

Source: OFweek