Single-mode light guiding in diamond waveguides directly written by a focused proton beam.

Ion-implanted waveguides were directly written in bulk single-crystal diamond by scanning a focused 2 MeV proton beam. By controlling the fluence and the lateral size of the proton beam, a bright and near-circular single-mode profile was observed. Propagation loss and effective refractive index of the guided mode were measured by the Fabry-Pérot technique, confirming single-mode guiding. Micro-Raman maps of the waveguides were used to visualize damage profiles and defect distributions induced by the proton beam. The demonstration of single-mode light guiding in our waveguides shows that direct proton beam writing is a promising tool in the rapid manufacture of integrated optical circuits in bulk diamond.

Subwavelength imaging through ion-beam-induced upconversion.

The combination of an optical microscope and a luminescent probe plays a pivotal role in biological imaging because it allows for probing subcellular structures. However, the optical resolutions are largely constrained by Abbe's diffraction limit, and the common dye probes often suffer from photobleaching. Here we present a new method for subwavelength imaging by combining lanthanide-doped upconversion nanocrystals with the ionoluminescence imaging technique. We experimentally observed that the ion beam can be used as a new form of excitation source to induce photon upconversion in lanthanide-doped nanocrystals. This approach enables luminescence imaging and simultaneous mapping of cellular structures with a spatial resolution of sub-30 nm.

High-gain optical waveguide amplifier based on proton beam writing of Nd:YAG crystal.

We report on an optical amplifier based on a Nd:YAG channel waveguide, which was fabricated by proton beam writing. Under the pumping of a continuous wave laser, the high-gain optical amplifications at single wavelength of 1064 nm and wavelength band of 1300 nm -1360 nm were obtained. The maximum gain was 24 dB/cm at 1064 nm and 6 dB/cm at 1319 nm, respectively. This work paves a way to apply proton beam written Nd:YAG waveguides as integrated optical amplifiers for the efficient amplification.

Proton beam writing of Nd:GGG crystals as new waveguide laser sources.

Focused proton beam writing has been utilized to fabricate optical channel waveguides in Nd:GGG crystals. The 1 MeV proton beam irradiation creates a local modified region with positive refractive index changes at the end of the proton trajectory, in which the channel waveguide could confine the light field in a symmetric way. Room-temperature laser emission has been achieved at 1063.7 nm, with absorbed pump power of 61 mW (at 808 nm). The obtained slope efficiency of the Nd:GGG waveguide laser system is as high as 66%, which is, to our best knowledge, the highest value for integrated lasers from ion beam processed channel waveguide systems.