| 1. |
- Gallo, Katia, et al.
(författare)
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Processing ultrafast optical signals in broadband telecom systems by means of cascaded quadratic nonlinearities
- 2006
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Ingår i: ICTON 2006. ; , s. 222-226
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Konferensbidrag (refereegranskat)abstract
- Quadratic optical nonlinearities offer several attractive features for the implementation of ultra-fast, low-noise and transparent telecom devices. Technological progress has dramatically increased their efficiency, driving a steady move towards practical applications. In this talk we shall discuss the use of cascaded quadratic interactions in LiNbO3 integrated devices for pulse diagnostics, format conversion and signal regeneration in ultra-fast multi-wavelength telecom systems.
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| 2. |
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| 3. |
- Lee, Kwang Jo, et al.
(författare)
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Analysis of acceptable spectral windows of quadratic cascaded nonlinear processes in a periodically poled lithium niobate waveguide
- 2011
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Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 19:9, s. 8327-8335
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Tidskriftsartikel (refereegranskat)abstract
- We report a systematic and comparative study of the acceptance bandwidths of two cascaded quadratic nonlinear processes in periodically poled lithium niobate waveguides, namely cascaded second-harmonic generation and difference-frequency generation (cSHG/DFG) and cascaded sum-frequency generation and difference-frequency generation (cSFG/DFG). We first theoretically and experimentally study the acceptance bandwidths of both the individual second-harmonic generation (SHG) and sum-frequency generation (SFG) processes in the continuous wave (CW) and pulsed-pump regimes. Our results show that the SHG bandwidth is approximately half that of the SFG process in the CW regime, whereas the SHG acceptance bandwidth can approach the CW SFG bandwidth limit when pulsed-pump is used. As a consequence we conclude that the tuning bandwidths of both cascaded processes should be similar in the pulsed pump regime once the pump pulse bandwidths approach that of SFG (i.e. the cSHG/DFG bandwidth is not limited by the CW SHG bandwidth). We confirm that this is the case experimentally.
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| 4. |
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| 5. |
- Lee, Kwang Jo, et al.
(författare)
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OTDM to WDM format conversion based on quadratic cascading in a periodically poled lithium niobate waveguide
- 2010
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Ingår i: Optics Express. - 1094-4087. ; 18:10, s. 10282-10288
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Tidskriftsartikel (refereegranskat)abstract
- We propose and demonstrate error-free conversion of a 40 Gbit/s optical time division multiplexed signal to 4 x 10 Gbit/s wavelength division multiplexed channels based on cascaded second harmonic and difference frequency generation in a periodically poled lithium niobate waveguide. The technique relies on the generation of spectrally (and temporally) flat linearly chirped pulses which are then optically switched with short data pulses in the nonlinear waveguide. Error-free operation was obtained for all channels with a power penalty below 2dB.
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| 6. |
- Lee, Kwang Jo, et al.
(författare)
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Phase sensitive amplification based on quadratic cascading in a periodically poled lithium niobate waveguide
- 2009
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Ingår i: Optics Express. - 1094-4087. ; 17:22, s. 20393-20400
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Tidskriftsartikel (refereegranskat)abstract
- We propose and demonstrate phase-sensitive amplification based on cascaded second harmonic generation and difference frequency generation within a periodically poled lithium niobate waveguide. Excellent agreement between our numerical simulations and proof-of-principle experiments using a 3-cm waveguide device operating at wavelengths around 1550 nm is obtained. Our experiments confirm the validity and practicality of the approach and illustrate the broad gain bandwidths achievable. Additional simulation results show that the maximum gain/attenuation factor increases quadratically with input pump power, reaching a value of +/- 19.0dB at input pump powers of 33 dBm for a 3 cm-long waveguide. Increased gains/reduced powers for a fixed gain could be achieved using longer crystals.
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| 7. |
- Liu, Sheng, et al.
(författare)
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Elimination of the chirp of optical pulses through cascaded nonlinearities in periodically poled lithium niobate waveguides
- 2010
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Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 35:22, s. 3724-3726
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Tidskriftsartikel (refereegranskat)abstract
- We propose and demonstrate a novel method for the elimination of arbitrary frequency chirp from short optical pulses. The technique is based on the combination of two cascaded second-order nonlinearities in two individual periodically poled lithium niobate waveguides. The proposed scheme operates independently of the spectral phase characteristics of the input pulse, producing a near-transform-limited output.
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| 8. |
- Liu, Sheng, et al.
(författare)
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Phase-regenerative wavelength conversion in periodically poled lithium niobate waveguides
- 2011
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Ingår i: Optics Express. - 1094-4087. ; 19:12, s. 11705-11715
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Tidskriftsartikel (refereegranskat)abstract
- We propose and experimentally demonstrate phase-regenerative wavelength conversion in periodically poled lithium niobate waveguides, using either: a single-stage implementation based on a simultaneous combination of two cascaded second-order nonlinear effects in a single periodically poled lithium niobate waveguide, or a two-stage implementation where two separate devices are used in sequence to give rise to the same nonlinear effects. The phase regeneration properties of the proposed wavelength conversion schemes are also investigated.
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| 9. |
- Liu, Sheng, et al.
(författare)
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Retiming of Short Pulses Using Quadratic Cascading in a Periodically Poled Lithium Niobate Waveguide
- 2011
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Ingår i: IEEE Photonics Technology Letters. - : IEEE. - 1041-1135 .- 1941-0174. ; 23:2, s. 94-96
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate an all-optical technique for the mitigation of timing jitter in short pulse transmission systems. The technique relies on pulse preshaping followed by optical switching in a periodically poled lithium niobate waveguide via cascaded second harmonic and difference frequency generation. The original data pulses are shaped into flat-top pulses to avoid conversion of their timing jitter into pulse amplitude noise at the output of the waveguide. Pulse retiming is confirmed by temporal measurements, while bit-error-rate measurements confirm good noise performance for the system.
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| 10. |
- Parmigiani, Francesca, et al.
(författare)
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Phase sensitive amplification based on cascaded SHG / DFG process in a periodically poled lithium niobate waveguide
- 2009
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Konferensbidrag (refereegranskat)abstract
- Phase-sensitive amplifiers (PSAs) have long been known to offer the possibility of amplification with a noise figure below the 3 dB quantum limit of phase insensitive amplifiers (PIA). Other advantages of the PSAs are the potential for optical signal processing, including all optical phase regeneration of phase encoded signals, dispersion compensation and coherent wavelength exchange. PSAs are usually demonstrated using highly nonlinear fibres as the nonlinear element. However, the use of cascaded sum- and difference-frequency generation (cSFG/DFG) of second-order nonlinearities in periodically poled lithium niobate (PPLN) waveguides offers a number of attractive features relative to corresponding fibre based PSA implementations including the prospect of compact devices, large operational bandwidths and importantly a far greater immunity to the effects of Stimulated Brillouin Scattering (SBS) of the pump beams which imposes performance limitations and adds complexity to silica fibre based PSA devices. Herein, we propose and demonstrate both theoretically and experimentally a new scheme for frequency non-degenerate PSA based on the cSHG/DFG process in a single PPLN waveguide
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