Diamond mirrors for high-power continuous-wave lasers.

High-power continuous-wave (CW) lasers are used in a variety of areas including industry, medicine, communications, and defense. Yet, conventional optics, which are based on multi-layer coatings, are damaged when illuminated by high-power CW laser light, primarily due to thermal loading. This hampers the effectiveness, restricts the scope and utility, and raises the cost and complexity of high-power CW laser applications.

Supercontinuum generation in angle-etched diamond waveguides.

We experimentally demonstrate on-chip supercontinuum generation in the visible region in angle-etched diamond waveguides. We measure an output spectrum spanning 670-920 nm in a 5-mm-long waveguide using 100-fs pulses with 187 pJ of incident pulse energy. Our fabrication technique, combined with diamond's broad transparency window, offers a potential route toward broadband supercontinuum generation in the UV domain.

Integrated high quality factor lithium niobate microdisk resonators.

Lithium Niobate (LN) is an important nonlinear optical material. Here we demonstrate LN microdisk resonators that feature optical quality factor ~10(5), realized using robust and scalable fabrication techniques, that operate over a wide wavelength range spanning visible and near infrared. Using our resonators, and leveraging LN's large second order optical nonlinearity, we demonstrate on-chip second harmonic generation with a conversion efficiency of 0.

Plasmonic superconducting nanowire single photon detector.

A theoretical analysis to enhance the quantum efficiency of a meander-line superconducting single photon detector without increasing the length or thickness of the active element is proposed. The general idea is to utilize the plasmonic nature of a superconducting layer to increase the surface absorption of the input optical signal. To satisfy both optical guiding and photon detection considerations of the design, a coefficient is introduced as a measure to maintain the device sensitivity while crossing over from the current crowding to vortex-based detection mechanisms.

Reduced dark counts in optimized geometries for superconducting nanowire single photon detectors.

We have experimentally compared the critical current, dark count rate and photo-response of 100nm wide superconducting nanowires with different bend designs. Enhanced critical current for nanowires with optimally rounded bends, and thus with no current crowding, are observed. Furthermore, we find that the optimally designed bend significantly reduces the dark counts without compromising the photo-response of the device.