Zn-indiffused diced ridge waveguides in MgO:PPLN generating 1 watt 780 nm SHG at 70% efficiency
SAM A. BERRY, LEWIS G. CARPENTER, ALAN C. GRAY, PETER G. R. SMITH, AND CORIN B. E. GAWITH
Abstract
We present a metallic zinc indiffused diced ridge waveguide in magnesium doped periodically poled lithium niobate (MgO:PPLN) capable of generating over 1 W of 780 nm with 70% efficiency. Our 40 mm long waveguide has near circular fundamental mode output with diameter 10.4 μm and insertion loss of -1.17 dB. Using a commercial 2 W EDFA-based system, the SHG output power did not exhibit roll-off at maximum available pump power.
CW demonstration of SHG spectral narrowing in a PPLN waveguide generating 2.5 W at 780 nm
Lewis G. Carpenter, Sam A. Berry, Alan C. Gray, James C. Gates, Peter G. R. Smith, and Corin B. E. Gawith
Abstract
Periodically poled lithium niobate (PPLN) waveguides are a proven and popular means for efficient wavelength conversion. However, conventional PPLN waveguides typically have small mode field diameters (MFD) (≲6 µm) or significant insertion and/or propagation losses, limiting their ability to operate at multi-watt power levels. In this work we utilise zinc indiffused PPLN ridge waveguides that have a larger MFD, favourable pump/SHG modal overlap, and low insertion losses. Here for the first time, we have demonstrated continuous wave (CW) spectral narrowing from a PPLN waveguide, both with high efficiency and multi-watt second harmonic generation (SHG). 2.5 W of 780 nm has been produced by SHG of an amplified 1560 nm telecom laser with a device efficiency of 58% in a 4.0-cm long ridge waveguide. We have modelled conversion efficiency and applied experimentally measured waveguide parameters to show excellent agreement to the SHG spectra. Spectral narrowing of the full width half maximum (FWHM) of 35.7% has been measured as the nonlinear drive is increased. This work demonstrates that single-pass, multi-watt, CW SHG at 780 nm is feasible from our PPLN waveguide in the large conversion regime.
A 750-mW, continuous-wave, solid-state laser source at 313nm for cooling and manipulating trapped 9Be+ ions
A. C. Wilson, C. Ospelkaus, A. P. VanDevender, J. A. Mlynek, K. R. Brown, D. Leibfried and D. J. Wineland
Abstract
We present a solid-state laser system that generates 750 mW of continuous-wave, single-frequency output at 313 nm. Sum-frequency generation with fiber lasers at 1550 and 1051 nm produces up to 2 W at 626 nm. This visible light is then converted to ultraviolet by cavity-enhanced second-harmonic generation. The laser output can be tuned over a 495-GHz range, which includes the 9Be+ laser cooling and repumping transitions. This is the first report of a narrow-linewidth laser system with sufficient power to perform fault-tolerant quantum-gate operations with trapped 9Be+ ions by use of stimulated Raman transitions.
All-solid-state continuous-wave laser systems for ionization, cooling and quantum state manipulation of beryllium ions
H.-Y. Lo, J. Alonso, D. Kienzler, B. C. Keitch, L. E. de Clercq, V. Negnevitsky and J. P. Home
Abstract
We describe laser systems for photoionization, Doppler cooling, and quantum state manipulation of beryllium ions. For photoionization of neutral beryllium, we have developed a continuous-wave 235 nm source obtained by two stages of frequency doubling from a diode laser at 940 nm. The system delivers up to 400 mW at 470 nm and 28 mW at 235 nm. For control of the beryllium ion, three laser wavelengths at 313 nm are produced by sum-frequency generation and second-harmonic generation from four infrared fiber lasers. Up to 7.2 W at 626 nm and 1.9 W at 313 nm are obtained using two pump beams at 1051 and 1551 nm. Intensity drifts of around 0.5 % per hour have been measured over 8 h at a 313 nm power of 1 W. These systems have been used to load beryllium ions into a segmented ion trap.
Upconversion-based lidar measurements of atmospheric CO2
L. Høgstedt, A. Fix, M. Wirth, C. Pedersen, and P. Tidemand-Lichtenberg
Abstract
For the first time an upconversion based detection scheme is demonstrated for lidar measurements of atmospheric CO2-concentrations, with a hard target at a range of 3 km and atmospheric backscatter from a range of ~450 m. The pulsed signals at 1572 nm are upconverted to 635 nm, and detected by a photomultiplier tube, to test how the upconversion technology performs in a long range detection system. The upconversion approach is compared to an existing direct detection scheme using a near-IR detector with respect to signal-to-noise ratio and quantum efficiency. It is for the first time analyzed how the field-of-view of a receiver system, for long range detection, depends critically on the parameters for the nonlinear up-conversion process, and how to optimize these parameters in future systems.
A simple 2 W continuous-wave laser system for trapping ultracold metastable helium atoms at the 319.8 nm magic wavelength
LR. J. Rengelink, R. P. M. J. W. Notermans, and W. Vassen
Abstract
High-precision spectroscopy on the 2 3S→2 1S transition is possible in ultracold optically trapped helium, but the accuracy is limited by the ac-Stark shift induced by the optical dipole trap. To overcome this problem, we have built a trapping laser system at the predicted magic wavelength of 319.8 nm. Our system is based on frequency conversion using commercially available components and produces over 2 W of power at this wavelength. With this system, we show trapping of ultracold atoms, both thermal (~0.2 μk) and in a Bose–Einstein condensate, with a trap lifetime of several seconds, mainly limited by off-resonant scattering.
Upconversion detector for range-resolved DIAL measurement of atmospheric CH4
L. Meng, A. Fix, M. Wirth, L. Høgstedt, P. Tidemand-Lichtenberg, C. Pedersen, & P. J. Rodrigo
Abstract
We demonstrate a robust, compact, portable and efficient upconversion detector (UCD) for a differential absorption lidar (DIAL) system designed for range-resolved methane (CH4) atmospheric sensing. The UCD is built on an intracavity pump system that mixes a 1064 nm pump laser with the lidar backscatter signal at 1646 nm in a 25-mm long periodically poled lithium niobate crystal. The upconverted signal at 646 nm is detected by a photomultiplier tube (PMT). The UCD with a noise equivalent power around 127 fW/Hz1/2 outperforms a conventional InGaAs based avalanche photodetector when both are used for DIAL measurements. Using the UCD, CH4 DIAL measurements have been performed yielding differential absorption optical depths with relative errors of less than 11% at ranges between 3 km and 9 km.
A picosecond Optical Parametric Oscillator synchronously pumped by an amplified gain-switched laser diode
F. Kienle, K. K. Cheng, S. Alam, C. B. E. Gawith, J. I.Mackenzie, D. C. Hanna, D. J. Richardson, and D. P. Shepherd
Abstract
We demonstrate a picosecond optical parametric oscillator synchronously pumped by a fiber-amplified gain-switched laser diode. Up to 7.3W at 1.54µm and 3.1W at 3.4µm is obtained at pulse repetition rates between 114.8 and 918.4MHz.
Optical Parametric Oscillator within 2.4–4.3 μm Pumped with a Nanosecond Nd:YAG Laser
D. B. Kolker, R. V. Pustovalova, M. K. Starikova, A. I. Karapuzikov, A. A. Karapuzikov, O. M. Kuznetsov, and Yu. V. Kistenev
Abstract
An optical parametric oscillator has been designed on the basis of MgO:PPLN periodic structure. A compact nanosecond Nd:YAG laser has been used as a pump source at 1.053 μm. The pump pulse length is 5–7 ns at a maximum pulse energy of 300 μJ and a frequency of 1000–5000 Hz. The oscillation threshold is 22 μJ at 3 μm and 48 μJ at 4.3 μm. The maximum conversion efficiency from incident pump power to the idler output is 3.9%.
Combining cw-seeding with highly nonlinear fibers in a broadly tunable femtosecond optical parametric amplifier at 42 MHz.
T. Steinle, S. Kedenburg, A. Steinmann, and H. Giessen
Abstract
We report on a precisely tunable and highly stable femtosecond oscillator-pumped optical parametric amplifier at a 41.7 MHz repetition rate for spectroscopic applications. A novel concept based on cw-seeding of a first amplification stage with subsequent spectral broadening and shaping, followed by two further amplification stages, allows for precise sub-nanometer and gap-free tuning from 1.35 to 1.75 μm and 2.55 to 4.5 μm. Excellent spectral stability is demonstrated with deviations of less than 0.008% rms central wavelength and 1.6% rms bandwidth over 1 h. Spectral shaping of the seed pulse allows precise adjustment of both the bandwidth and the pulse duration over a broad range at a given central wavelength. Transform-limited pulses nearly as short as 107 fs are achieved. More than half a Watt of average power in the near- and more than 200 mW in the mid-infrared with power fluctuations less than 0.6% rms over 1 h provide an excellent basis for spectroscopic experiments. The pulse-to-pulse power fluctuations are as small as 1.8%. Further, we demonstrate for the first time, to the best of our knowledge, that by using hollow-core capillaries with highly nonlinear liquids as a host medium for self-phase modulation, the signal tuning range can be extended and covers the region from 1.4 μm up to the point of degeneracy at 2.07 μm. Hence, the idler covers 2.07 to 4.0 μm.
