Session Index

Thin-film lithium niobate enables to combine the advantages of the lithium niobate material with nanoscale optical elements. Here, I will review our recent results in the realization of nanostructured lithium-niobate components for nonlinear frequency conversion. Special emphasis is on the use of these structures as sources of correlated photon-pairs.

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We show that the speckle phase error incurred when the laser spot is scanned over the diffusing surface can be made as low as 10..20-m for object sizes in the range 3..10-cm. This result is new, at the best of our knowledge, because it is usually assumed that when the spot moves of its size the phase becomes uncorrelated and the measurement can't be done anymore. We carry out numerical simulations of the process, and derive an analytical model to evaluate the phase error and the NED (noise equivalent displacement) of the profile measurement by SMI (self-mixing interferometer).

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We present the study of a near-infrared free-electron laser consisting of a 31-um long dielectric grating with a 310-nm grating period in a 400-nm thick silicon waveguide on a glass substrate. When driven by a ~50-keV electron flying 100 nm above the structure, the nano-grating generates a laser-like radiations at ~1.5 micron via Bragg and backward-wave resonances. This work paves the way to miniaturize a bulky free-electron laser to a chip-size device.

 

Strong coupling between an atom and a cavity has been utilized for quantum photonic devices. The alignment between an atom and a cavity needs atom trapping and high vacuum equipment, which are hardly to be integrated into a microchip. Here, DNA strands are used to connect a gold nanoparticle and a gold film to construct a nanocavity and simultaneously integrate a few fluorophores to form a strong coupling unit. This method produces high cavity yield and strong coupling yield. Combination of this method with e-beam lithography can further position strong coupling units on a specific location of a microchip.


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We fabricated a high-power distributed feedback (DFB) laser. In the experiment, the measured temperature and the injected current are changed, we observed the difference in the frequency spectrum. In the microwave measurement, it is found that the switching between DFB mode and FP mode will affect the oscillation frequency.

 

In this study, we design the structure of flip-chip tunnel junction VCSEL to improve speed, output power and conversion efficiency for medium and long-distance sensing. Through the design of flip-chip structure and tunnel junction, the PCE can improve to 57.8%.