| 1. |
- Agate, B., et al.
(författare)
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Portable ultrafast blue light sources designed with frequency doubling in KTP and KNbO3
- 2004
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 1077-260X .- 1558-4542. ; 10:6, s. 1268-1276
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate an effective means of achieving compact, truly portable, and entirely self-contained ultrafast blue light sources. Using a variety of nonlinear media to achieve simple second-harmonic generation of a femtosecond Cr:LiSAF laser, we investigate the relative merits of aperiodically poled bulk and waveguide nonlinear crystals in comparison to periodically poled structures. Such a compact and convenient source of ultrashort laser pulses in the blue spectral region could be of great interest for on-site applications spanning a host of disciplines, such as biomedical imaging, optical micromanipulation, and high-resolution spectroscopy.
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| 2. |
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| 3. |
- Korkishko, Y. N., et al.
(författare)
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The SHG-response of different phases in proton exchanged lithium niobate waveguides
- 2000
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 1077-260X .- 1558-4542. ; 6:1, s. 132-142
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Tidskriftsartikel (refereegranskat)abstract
- Reflection second-harmonic generation from the polished waveguide end face is used to investigate the second-order nonlinear optical properties of as-exchanged and annealed proton-exchanged (PE) waveguides in different HxLi1-xNbO3 phases. A detailed correlation is done between the nonlinear properties, the processing conditions, the refractive index changes, and the optical losses of the waveguides. It is found that for the direct PE samples, where the beta(4), beta(3), and beta(1) phases are generated at the surface, the nonlinearity in the guide is strongly reduced by more than 85% of its bulk value, while for waveguides prepared in the beta(2) phase, the nonlinear coefficient is about 55% of the bulk one. A consequence is that the step-like beta(i)-phase PE LiNbO3 waveguides with large refractive index increase are advantageous for efficient SHG in Cherenkov configuration. The nonlinearity, strongly reduced after the initial proton exchange, is found to be restored and even increased after annealing, However, this apparent increase of the nonlinearity is accompanied by a strong degradation of the quality of the second-harmonic generation reflected beam in the region of initial waveguides due to beam scattering. The graded proton exchange technique and dilute melt proton exchange have been shown to produce high-quality waveguides with essentially undergraded nonlinear optical properties. It has been also shown that the nonlinear properties of annealed proton exchanged LiNbO3 waveguides can be effectively recovered by the reverse proton exchange technique, The results obtained are important for the design, fabrication, and optimizing of guided-wave nonlinear optical devices in LiNbO3.
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| 4. |
- Qiu, Min, et al.
(författare)
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Wave propagation through a photonic crystal in a negative phase refractive-index region
- 2003
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 1077-260X .- 1558-4542. ; 9:1, s. 106-110
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Tidskriftsartikel (refereegranskat)abstract
- The wave propagation through a photonic crystal with a triangular lattice of air holes realized in the InP-InGaAsP heterostructure are studied theoretically for the transverse magnetic modes. The photonic crystal possesses a negative refractive index, and the self-focus of the beam is successfully observed. The weak side beams are observed due to high-order Bloch waves in the photonic crystal. The coupling efficiency for the outgoing waves to a waveguide is also studied.
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| 8. |
- Osvay, Karoly, et al.
(författare)
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Angular dispersion and temporal change of femtosecond pulses from misaligned pulse compressors
- 2004
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - 1077-260X. ; 10:1, s. 213-220
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Tidskriftsartikel (refereegranskat)abstract
- A misaligned stretcher or compressor in a chirped pulse amplification laser introduces residual angular dispersion into the beam, resulting in temporal distortion of the pulse. We demonstrate that an imaging spectrograph is capable for Measuring the angular dispersion of a laser beam by an accuracy of 0.2 murad/min. Using this technique, the analytical expressions of residual angular dispersion of misaligned prism and grating compressors are experimentally proved. Temporal degradations of short pulses due to angular dispersion are studied by measuring the, temporal stretch of 16-fs pulses, while the issues of contrast deterioration are also discussed. It is proved that the simultaneous; measurement of angular dispersion and pulse duration offers the most precise alignment procedure of prismatic and grating compressors.
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