Ultrafast Tunable Lasers With Integrated Photonics

Continuous-wave light detection and ranging (LiDAR) systems may benefit from a new ultrafast tunable laser based on low-loss lithium niobate integrated photonics. The device outperforms earlier similar lasers in terms of laser linewidth and has a high rate of frequency adjusting.

The substantial optical signal losses and volatile nature of today’s programmable photonic integrated circuits (PICs) make it impossible for them to maintain their intended state. Lithium niobate, frequently used in optical modulators (devices that modulate the frequency or intensity of transmitted light), has outstanding optical and electro-optical qualities that may solve this issue.

Recently, lithium niobate has become a desirable substrate material for PICs and has the potential to produce circuits with fewer optical losses (an ultrafast tunable laser light beam can pass through them with less power loss). The material has a high “Pockels coefficient,” which allows its optical properties to be controlled using an electric field and can support high optical power levels.

In their latest discovery, the scientists combined a distributed feedback laser with a silicon nitride-lithium niobate [(Si3N4)–LiNbO3] photonic integrated circuit to create a hybrid device. The latter comprises silicon nitride waveguides covered with a thin coating of lithium niobate. Despite its seeming simplicity, this assembly took the researchers years to complete since it required the precise bonding of a LiNbO3 wafer that was 4 inches wide to a Damascene Si3N4 wafer the same width.

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