With an emission bandwidth approaching an octave, titanium-doped sapphire lasers are key tools for producing solid-state lasing across visible and near-infrared bands. However, existing titanium-doped sapphire laser systems require high pump power. They mostly rely on expensive tabletop components, restricting them to laboratory settings.
A team of researchers has developed the first chip-scale titanium-doped sapphire laser—a breakthrough with applications ranging from atomic clocks to quantum computing and spectroscopic sensors. This is the world’s first titanium-doped sapphire (Ti: Sa) laser integrated with a chip-scale photonic circuit.
It provides the widest gain spectrum yet seen on a chip—paving the way for numerous new applications.
The low threshold of the laser is the key. The Tang lab’s system has a threshold of roughly 6.5 milliwatts, whereas standard titanium-doped sapphire lasers had a threshold of more than 100 milliwatts. They think they can further lower it to 1 milliwatt with some adjustments. Their method is also compatible with the gallium nitride optoelectronics family, frequently utilised in blue LEDs and lasers.
Scientists noted, “We demonstrate Ti: Sa lasing from 730 nm to 830 nm by tightly confining the pump and lasing modes to a single microring resonator, reducing the lasing threshold by orders of magnitude down to 6.5 mW when compared with the free-space Ti: Sa lasers.”
“Due to the low threshold, turn-key Ti: Sa laser operation is achieved by leveraging a commercially available indium gallium nitride pump diode. Our prototype photonic-circuit-integrated Ti: Sa laser opens a reliable pathway for broadband tunable lasers in the next generation of active–passive-integrated visible photonics.”
- Wang, Y., Holguín-Lerma, J.A., Vezzoli, M. et al. Photonic-circuit-integrated titanium: sapphire laser. Nat. Photon. (2023). DOI: 10.1038/s41566-022-01144-2