Recently, researchers at Stanford University have made a breakthrough in laser manufacturing.
They successfully developed and manufactured titanium sapphire lasers on a chip. This innovative achievement not only reduced the size of the laser by four orders of magnitude (i.e., reduced it to one ten-thousandth of the original), but also reduced the cost by three orders of magnitude (i.e., only one thousandth of the original price).
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"This is a disruptive breakthrough in the traditional model," said Professor Jelena Vučković, a professor of global leadership and an authority in the field of electronic engineering, excitedly.
As senior author of the paper detailing the chip-scale titanium sapphire laser in the journal Nature, she is excited about the future: "Soon, any lab will be able to have hundreds of these high-performance lasers on a single chip, without having to rely on bulky and expensive traditional equipment. It will also be so easy to operate that you can even drive it with a green laser pointer."
Joshua Yang, a PhD candidate in the lab, further elaborates on the far-reaching impact of this technology: "As we make the leap from desktop devices to making producible products on chips, these powerful lasers will be able to be used in a variety of important fields at a very low cost."
He completed this groundbreaking research with colleagues in Professor Vuckovic's Nanoscale and Quantum Photonics Laboratory, including research engineer Kasper Van Gasse and postdoctoral scholar Daniil M. Lukin.
From a technical perspective, titanium sapphire lasers are so popular because they have the largest "gain bandwidth" of any laser crystal. This means that titanium sapphire lasers can produce a wider range of wavelengths than other lasers.
In addition, their light pulses are fired extremely quickly, once every quadrillionth of a second. These outstanding performance characteristics will undoubtedly greatly promote the widespread application and in-depth development of laser technology in various fields.
To create this new laser, they first precisely covered a layer of real sapphire crystal on the silicon dioxide platform and laid a layer of titanium sapphire on it.
Then, after fine grinding, etching and polishing, the titanium sapphire was reduced to an ultra-thin layer of only a few hundred nanometers thick. Next, the research team carefully drew the pattern of the waveguide in this ultra-thin material.
This miniaturized design brings significant advantages. From a mathematical point of view, intensity is the ratio of power to area. Therefore, when maintaining the same power as a large-scale laser, the intensity of the laser will be significantly improved due to the reduction in area. The researchers pointed out: "The small size of the laser actually helps us improve efficiency."
In addition, to further improve the performance of the laser, the research team also added a micro heater. This heater can heat the light passing through the waveguide, allowing Jelena Vučković's team to flexibly adjust the wavelength of the emitted light between 700-1000 nanometers.
This titanium sapphire laser on a microchip shows broad application prospects in many fields. In quantum physics, it offers a cheap and practical solution for shrinking the size of state-of-the-art quantum computers.
And in neuroscience, Stanford researchers foresee direct applications in optogenetics, a field that allows scientists to control and influence neuronal activity inside the brain through light, despite the relatively bulky fiber-optic equipment currently used.
Looking ahead, the team will continue to refine the design of chip-scale titanium sapphire lasers and explore the possibility of mass production on wafers, producing thousands of lasers at a time.
This summer, Joshua Yang will receive his doctorate based on this research and work on bringing this technology to market. He confidently stated: "We can put thousands of lasers on a 4-inch wafer, and the cost of each laser will approach zero. This will undoubtedly trigger a technological revolution."
