Synthetic single-crystal diamond has recently emerged as a promising platform for Raman lasers at exotic wavelengths due to its giant Raman shift, large transparency window, and excellent thermal properties yielding a greatly enhanced figure of merit compared to conventional materials. To date, diamond Raman lasers have been realized using bulk plates placed inside macroscopic cavities, requiring careful alignment and resulting in high threshold powers (W–kW range). Here we demonstrate an on-chip Raman laser based on fully integrated, high-quality-factor, diamond racetrack microresonators embedded in silica. Pumping at telecom wavelengths, we show Stokes output discretely tunable over a ∼100  nm bandwidth around 2 μm with output power >250 μW, extending the functionality of diamond Raman lasers to an interesting wavelength range at the edge of the mid-infrared spectrum. Continuous-wave operation with only ∼85  mW pump threshold power in the feeding waveguide is demonstrated along with continuous, mode-hop-free tuning over ∼7.5  GHz in a compact, integrated-optics platform.

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On-chip diamond Raman laser

Raman lasers based on c-Nd:YVO4 crystals can generate 1178 nm Stokes line, which can be frequency-doubled to realize 589 nm sodium lasers. We make comparative experimental studies of c-Nd:YVO4/YVO4 Raman lasers and c-Nd:YVO4 self-Raman lasers. About these two kinds of lasers, the output characteristics of power, center wavelength and beam quality are measured and compared.

Comparison of c -Nd:YVO 4 /YVO 4 raman lasers and c -Nd:YVO 4 self-Raman lasers

The realization of an integrated diamond photonic platform, based on a thin single crystal diamond film on top of a silicon dioxide/silicon substrate, is reported. Using this approach, we demonstrate high-quality factor single crystal diamond race-track resonators, operating at near-infrared wavelengths (1550 nm). The devices are integrated with low-loss diamond waveguides terminated with polymer pads (spot size converters) to facilitate in- (out-) coupling of light from (to) an optical fiber. Optical characterization of these resonators reveal quality factors as high as ∼250 000 and overall insertion losses as low as 1 dB/facet. Scattering induced mode splitting as well as signatures of nonlinear effects such as optical bistability are observed at an input pump power of ∼100 mW in the waveguides.

Integrated High-Quality Factor Optical Resonators in Diamond

Efficient Raman frequency conversion of high‐power fiber lasers in diamond

Nonlinear conversion of unpolarized beams to lower frequencies is generally inefficient in c(2) materials, as it is challenging to achieve phase-matching for input ordinary and extraordinary beams simultaneously in the normal dispersion regime. Here, we show that cubic Raman crystals having doubly and triply degenerate (E and F type) modes provide a method for efficient nonlinear frequency downconversion of an unpolarized beam and yield a linearly polarized output state. Using Mueller calculus, optimal crystal directions for such polarization conversion are determined. Using diamond, an example of an F-class Raman crystal, we have verified that such conversion is possible with near quantum-defect-limited slope efficiency and a linear polarization contrast of more than 23.9 dB.

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Polarization conversion in cubic Raman crystals

We report a pulsed Raman laser at 1193 nm based on synthetic diamond crystals with a record output power of 24.5 W and a slope efficiency of 57%. We compared the performance of an anti-reflection coated crystal at normal incidence with a Brewster cut sample. Raman oscillation was achieved at both room temperature and under cryogenic operation at 77 K. Modeling of these experiments allowed us to confirm the value of Raman gain coefficient of diamond, which was found to be 13.5 ± 2.0 cm/GW for a pump wavelength of 1030 nm.

High average power diamond Raman laser

The invention generally relates to system and method for recovering sodium bicarbonate from a solid waste, and more particularly to a method and system for recovering sodium bicarbonate from fly ash of a coal fired plant collected downstream of an injection process for pollution reduction from the industrial process.

Dry sorbent injection (dsi) recovery system and method thereof

La presente invention concerne en general un systeme et un procede permettant de recuperer du bicarbonate de soude a partir de dechets solides et plus particulierement un procede et un systeme permettant de recuperer du bicarbonate de soude provenant de cendres volantes d'une centrale alimentee au charbon, collecte en aval d'un processus d'injection en vue de la reduction de la pollution due aux procedes industriels.

Jean-Philippe Feve

Papers

High average power diamond Raman laser

Dry sorbent injection (dsi) recovery system and method thereof

Système de récupération d'injection de sorbants secs (dsi) et son procédé