排序方式: 共有21条查询结果,搜索用时 15 毫秒
1.
Vodopyanov KL Levi O Kuo PS Pinguet TJ Harris JS Fejer MM Gerard B Becouarn L Lallier E 《Optics letters》2004,29(16):1912-1914
We demonstrate an optical parametric oscillator (OPO) based on GaAs. The OPO utilizes an all-epitaxially-grown orientation-patterned GaAs crystal that is 0.5 mm thick, 5 mm wide, and 11 mm long, with a domain reversal period of 61.2 microm. Tuning either the near-IR pump wavelength between 1.8 and 2 microm or the temperature of the GaAs crystal allows the mid-IR output to be tuned between 2.28 and 9.14 microm, which is limited only by the spectral range of the OPO mirrors. The pump threshold of the singly resonant OPO is 16 microJ for the 6-ns pump pulses, and the photon conversion slope efficiency reaches 54%. We also show experimentally the possibility of pump-polarization-independent frequency conversion in GaAs. 相似文献
2.
Vasilyev S Schiller S Nevsky A Grisard A Faye D Lallier E Zhang Z Boyland AJ Sahu JK Ibsen M Clarkson WA 《Optics letters》2008,33(13):1413-1415
A narrow-linewidth mid-IR source based on difference-frequency generation of an amplified 1.5 microm diode laser and a cw Tm-doped fiber laser in orientation-patterned (OP) GaAs has been developed and evaluated for spectroscopic applications. The source can be tuned to any frequency in the 7.6-8.2 microm range with an output power of 0.5 mW. The measured characteristics of the OP-GaAs sample demonstrate a high quality of the material. 相似文献
3.
S. Vasilyev H.-E. Gollnick A. Nevsky A. Grisard E. Lallier B. Gérard J. Jimenez S. Schiller 《Applied physics. B, Lasers and optics》2010,100(4):737-747
The effects of coupling between clockwise and counterclockwise modes in ring resonators due to back reflections from QPM gratings
in nonlinear crystals are investigated. We demonstrate, using simulations, that the non-phase-matched back reflection due
to typical imperfections of the QPM grating has a relevant magnitude and can give rise to the coupling. We developed an analytical
model and evaluated parameters of a singly resonant OPO in the presence of this coupling, which indicates that the threshold
pump power is doubled in the limit of strong coupling. We also evaluated the effect of the coupling with respect to resonant
power enhancement for cavity-enhanced nonlinear frequency mixing applications, finding that the enhancement is reduced by
up to a factor four. Experimental observations based on PPLN and orientation-patterned GaAs crystals and model predictions
are in good agreement. We propose and demonstrate a method for active stabilization of ring resonators with mode coupling
that relies on the dissimilarity of the coupled forward and backward modes. 相似文献
4.
Lombard L Brignon A Huignard JP Lallier E Lucas-Leclin G Georges P Pauliat G Roosen G 《Optics letters》2004,29(9):989-991
The multimode and depolarized output beam of a highly multimode diode-pumped Yb-doped fiber amplifier is converted to a diffraction-limited, linearly polarized beam by a self-referencing two-wave-mixing process in an infrared-sensitive photorefractive crystal (Rh:BaTiO3). As much as 11.6 W of single-mode output is achieved with a 78% multimode-to-single-mode photorefractive conversion efficiency. 相似文献
5.
Chausson F Sanglier S Leize E Hagège A Bridges CR Sarradin PM Shillito B Lallier FH Zal F 《Micron (Oxford, England : 1993)》2004,35(1-2):31-41
Segonzacia mesatlantica (Crustacea; Decapoda; Brachyura) is the only endemic crab species known from the Mid-Atlantic Ridge (MAR) hydrothermal vents. Known from all explored sites in the Atlantic, its wide distribution makes this species a model to study physiological adaptation, and specifically respiratory strategies. Native haemocyanin (Hc) comprises four non-covalent associations in equilibrium formed by monomers, hexamers, dodecamers and octadecamers made up of approximately 75 kDa polypeptide chains. Four different amino acid chains are observed with a molecular mass ranging from 75,234 to 75,972 Da. Experiments carried-out under pressure suggested that the percentage of monomer increased in the haemolymph under hypoxic condition. We have also observed a shift of the proportion of the two dodecamer series, suggesting a rapid modification of the Hc phenotype between hypoxic and hyperoxic conditions. Native Hc possesses a high oxygen affinity ( P50 = 2.2 Torr at 15 degrees C and pH 7.5), a large Bohr effect (Deltalog P50 / DeltapH approximately -2.7) and a slightly reverse temperature effect (DeltaH = +17.19 kJ mol(-1). The composition of Segonzacia haemolymph is similar to that of other littoral species except for the large enrichment in free copper and zinc. As for other species from hydrothermal vent sites, Segonzacia haemolymph possesses a higher buffer capacity than littoral species. Moreover, species from the hydrothermal vent decapods from Pacific hydrothermal vent that encounter higher CO2 content in their environment have a higher buffer capacity than Atlantic vent species. The results presented are discussed in relation with the physico-chemical characteristics of the hydrothermal vent environment. 相似文献
6.
Bruneaux M Rousselot M Leize E Lallier FH Zal F 《Current protein & peptide science》2008,9(2):150-180
Understanding the function of macromolecular complexes is related to a precise knowledge of their structure. These large complexes are often fragile high molecular mass noncovalent multimeric proteins. Classical biochemical methods for determination of their native mass and subunit composition were used to resolve their quaternary structure, sometimes leading to different models. Recently, the development of mass spectrometry and multi-angle laser light scattering (MALLS) has enabled absolute determination of native masses and subunit masses. Electrospray ionization mass spectrometry (ESI-MS) was used in denaturing and native conditions to probe subunit composition and noncovalent assemblies masses up to 2.25 MDa. In a complementary way, MALLS provides mass and size estimation in various aqueous solvents. ESI-MS method can also give insights into post-translational modifications (glycosylation, disulfide bridges ). By combining native mass and subunit composition data, structural models can be proposed for large edifices such as annelid extracellular hexagonal bilayer hemoglobins (HBL Hb) and crustacean hemocyanins (Hc). Association/dissociation mechanisms, protein-protein interactions, structural diversity among species and environmental adaptations can also be addressed with these methods. With their absolute mass determination, the very high precision of spectrometry and the versatile nature of light scattering, ESI-MS and MALLS have provided a wealth of data helping to resolve parts of controversies for HBL-Hb models and opening access to new fields of investigation in structural diversity and molecular adaptation. In this review we will focus on annelid HBL-Hb and on crustacean Hc and on the original contributions of ESI-MS and MALLS in this field. 相似文献
7.
8.
Cascaded second-harmonic and sum-frequency generation were used to obtain the third harmonic of a CO(2) laser in a single quasi-phase-matched GaAs crystal. Both continuous-wave and pulsed regimes with a single-pass configuration were studied. The continuous case confirmed the good capability of the GaAs stack to bear high average power density. In the pulsed regime a 0.66% peak power conversion efficiency was achieved for the third harmonic when the laser was pumping at 8.2 MW/cm(2) , in fair agreement with theoretical predictions. 相似文献
9.
We report on the fabrication and characterization of 5-mm-long quasi-phase-matched diffusion-bonded GaAs crystals designed for frequency doubling of a CO(2) laser. Second-harmonic generation of a pulsed laser yielded up to 24% peak power efficiency at 20 MW/cm(2) . Tunability and laser damage threshold are also investigated. 相似文献
10.
We present a technique to convert a multimode-transverse beam obtained from a multimode large core fiber amplifier into a
single-mode beam by means of two-wave mixing in an infrared-sensitive Rh:BaTiO3 crystal.
Received: 26 March 2001 / Revised version: 27 March 2001 / Published online: 27 April 2001 相似文献