Ultra-Narrow Linewidth External Cavity Tunable Lasers At Any Wavelength

LioniX International manufactures narrow linewidth external cavity tunable lasers at wavelength ranges around 1550 nm, 850 nm, 780 nm, and 680 nm. With our hybrid photonic IC technology, we develop custom lasers with tailored specifications.

Narrow linewidth light sources are essential for the proper functioning of photonic integrated circuits (PICs). This necessity prompted research into light generation on PICs, so that the same circuit produces and modulates light to carry and process signals. However, active photonic platforms that generate light have higher optical losses, and low optical loss passive platforms are unable to generate light of their own. Therefore, hybrid integration of active and passive platforms remains a powerful method of device realization.

Our tunable lasers use hybrid integration by delegating light generation to an active platform and coupling the output to an external cavity integrated on our ultra-low loss platform, TriPleX®. Our cavity then tunes the light to a precise narrow band and passes it on to the rest of the circuit.

External cavity tunable laser design

The unique design features a long external cavity acting as a tunable mirror for one or more gain chips. The TriPleX® waveguide platform, based on silicon nitride (Si3N4), offers ultra-low propagation losses (0.1 dB/cm) and broad transparency (405 to 2350 nm) for very high Q cavities and a wide range of possible laser wavelengths.

A schematic of the external cavity tunable laser by LioniX International

Schematic diagram of the external cavity tunable laser.

Precise wavelength tuning across a wide range is made possible using two micro-ring resonators and heating elements. Additional functionalities, like filtering and switching and delay lines, can be added to the external cavity chip. This customizability allows designers to integrate more photonic functions on-chip without additional inter-chip optical losses, and it reduces assembly difficulty and cost during fabrication.

The upshot is scalability: scalable function integration and scalable production volumes.

Custom integrated lasers

As far back as 2017, a TriPleX®-powered external cavity laser with a 1550 nm central wavelength was able to keep its linewidth down to 290 Hz, a record-narrow peak. Moreover, the laser had an 81 nm tunability range. This achievement was made possible by the ultra-low propagation losses of the TriPleX® platform and the low signal cost of its integration with active platforms (< 1 db/facet). We then continued to produce integrated lasers for the multitude of applications in which our PICs have been deployed. There are now multiple variations of the laser which operate at radically different wavelengths, such as 850 nm for life science applications, 780 nm for optical coherence tomography, and 680 nm for machine vision and visible light applications.

As our waveguide platform is transparent for a broad wavelength range, other lasers were soon developed. As clients and research projects seek new wavelengths, our list of developed lasers grows. This year at Photonics West, two new lasers were presented: 800 nm and 637 nm. The broad transparency of our photonic platform means that we can develop an external cavity tunable laser for any wavelength between 2350 and 405 nm.

The result is a small form factor (< 1 cm), temperature-resilient (down to 3 K), mechanically sturdy (up to 40 g) external cavity tunable laser tailor made for your application. Contact us to discuss custom development, or try out the 1550 nm laser with other standard building blocks in our multi project wafer service.

A closeup of an 850 nm tunable laser, featuring the gain and cavity chips coupled to a fiber array.