Four nanophotonic resonators, each slightly different in geometry, generates different colors of visible light from the same near-infrared pump laser.
Credit: NIST
In two new studies, researchers at the National Institute of Standards and Technology (NIST) have greatly improved the efficiency and power output of a series of chip-scale devices that generate laser light at different colors while all using the same input laser source.
Many quantum technologies, including miniature optical atomic clocks and future quantum computers, will require simultaneous access to multiple, widely varying laser colors within a small region of space. For instance, up to six different laser colors are needed for all the steps required for a leading atom-based design for quantum computation, including preparing the atoms, cooling them, reading out their energy states, and performing quantum logic operations.
To create multiple laser colors on one chip, NIST researcher Kartik Srinivasan and his colleagues have spent the last few years studying nonlinear optical devices, such as those made of silicon nitride, which have a special property: The color of laser light entering the device can differ from the color that exits. In their experiment, incoming light is converted into two different colors—which correspond to two different frequencies. For instance, near-infrared laser light incident on the material is converted into shorter-wavelength visible laser light (at higher frequency than the source) and longer-wavelength infrared laser light (at lower frequency).
In previous work, the team demonstrated that this conversion process, known as optical parametric oscillation, can occur within a silicon nitride microresonator, a ring-shaped device small enough to be fabricated on a chip. The light races around the ring some 5,000 times, building a high enough intensity for the silicon nitride to convert it into the improved scale color conversion lasers could enable generation quantum devices
