The Stanford University team has manufactured the first practical chip grade titanium sapphire laser

According to a report in Nature on June 26th, a team from Stanford University in the United States has developed a titanium sapphire laser on a chip. Whether in terms of scale efficiency or cost, this achievement is a huge progress.

Image source: Nature website
Titanium sapphire lasers are indispensable in many fields such as cutting-edge quantum optics, spectroscopy, and neuroscience, but they have not been widely applied in the real world. Because this type of laser is usually large in size and expensive, costing hundreds of thousands of dollars per unit, and requiring other high-power equipment (priced at approximately $30000 per unit) to maintain operation.

To solve this problem, researchers first laid a large layer of titanium sapphire on the silica platform; Grind, etch, and polish the titanium sapphire into an extremely thin layer, only a few hundred nanometers thick; Then, design a vortex composed of tiny ridges on the thin layer. These ridges are like fiber optic cables, guiding light to circulate continuously and gradually increasing in intensity. This mode is called a waveguide. Compared with other titanium sapphire lasers, this prototype has reduced its size by 4 orders of magnitude (equivalent to one thousandth of the original) and reduced its cost by 3 orders of magnitude (equivalent to one thousandth of the original).

The remaining part is a microscale heater that can heat the light passing through the waveguide, allowing researchers to change the wavelength of the emitted light and adjust the wavelength range to between 700-1000 nanometers, from red light to infrared light.

In quantum physics, this new laser can significantly reduce the scale of state-of-the-art quantum computers; In the field of neuroscience, it can be applied in optogenetics, allowing scientists to control neurons by guiding light inside the brain through relatively large optical fibers; In ophthalmology, it may be combined with chirped pulse amplification technology in laser surgery to achieve new applications, or provide cheaper and more compact optical coherence tomography technology to evaluate retinal health.

Currently, constantly updated technology allows many laboratories to have ultra small lasers on a single chip, rather than a large and expensive laser. Small size lasers actually help improve efficiency - mathematically speaking, intensity is equal to power divided by area. Therefore, maintaining the same power as large lasers but reducing their concentrated area will result in a significant increase in intensity. More importantly, these compact and powerful lasers can quickly leave the laboratory and serve many different important applications.

Source: Chinese Academy of Sciences