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790 KiB

Open AccessArticle

Four-Wave Optical Parametric Amplification in a Raman-Active Gas

by Yuichiro Kida and Totaro Imasaka

Photonics 2015, 2(3), 933-945; https://doi.org/10.3390/photonics2030933 - 31 Aug 2015

Cited by 2 | Viewed by 4924

Four-wave optical parametric amplification (FWOPA) in a Raman-active medium is experimentally investigated by use of an air-filled hollow fiber. A femtosecond pump pulse shorter than the period of molecular motion excites the coherent molecular motion of the Raman-active molecules during the parametric amplification [...] Read more.

Four-wave optical parametric amplification (FWOPA) in a Raman-active medium is experimentally investigated by use of an air-filled hollow fiber. A femtosecond pump pulse shorter than the period of molecular motion excites the coherent molecular motion of the Raman-active molecules during the parametric amplification of a signal pulse. The excited coherent motion modulates the frequency of the signal pulse during the parametric amplification, and shifts it to lower frequencies. The magnitude of the frequency redshift depends on the pump intensity, resulting in intensity-dependent spectral characteristics that are different from those in the FWOPA induced in a noble-gas-filled hollow fiber. Full article

(This article belongs to the Special Issue Nonlinear Fiber Optics)

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314 KiB

Open AccessArticle

Four-Wave Mixing of a Laser and Its Frequency-Doubled Version in a Multimode Optical Fiber

by Hamed Pourbeyram and Arash Mafi

Photonics 2015, 2(3), 906-915; https://doi.org/10.3390/photonics2030906 - 27 Aug 2015

Cited by 12 | Viewed by 5072

Abstract

It is shown that it is possible to couple a laser beam and its frequency-doubled daughter into a multimode optical fiber through the four-wave mixing nonlinear process and generate a new wavelength. The frequency-doubled daughter can be generated in an external crystal with [...] Read more.

It is shown that it is possible to couple a laser beam and its frequency-doubled daughter into a multimode optical fiber through the four-wave mixing nonlinear process and generate a new wavelength. The frequency-doubled daughter can be generated in an external crystal with a large second order nonlinearity. It is argued that while this possibility is within the design parameter range of conventional multimode optical fibers, it necessitates a lower-bound for the core-cladding refractive index contrast of the multimode optical fiber. Full article

(This article belongs to the Special Issue Nonlinear Fiber Optics)

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1166 KiB

Open AccessArticle

Dynamics of a Low-Dimensional Model for Short Pulse Mode Locking

by Edward D. Farnum and J. Nathan Kutz

Photonics 2015, 2(3), 865-882; https://doi.org/10.3390/photonics2030865 - 03 Aug 2015

Cited by 9 | Viewed by 3811

Abstract

Emerging ultra-fast mode-locked lasers are now capable of generating pulses in the few to sub-femtosecond regime. Using recent theoretical innovations around the short pulse equation, we characterize the mode locking dynamics using a low-dimensional representation of the pulse parameters. The theory is formulated [...] Read more.

Emerging ultra-fast mode-locked lasers are now capable of generating pulses in the few to sub-femtosecond regime. Using recent theoretical innovations around the short pulse equation, we characterize the mode locking dynamics using a low-dimensional representation of the pulse parameters. The theory is formulated using a variational approach, since linearization of the exact solution is not tractable. The dominant dynamics can be characterized in a geometrical way using phase-plane analysis. Of note is our ability to determine the underlying bifurcations that occur due to changes in the fiber laser cavity parameters, including the onset of the multi-pulsing instability. The theory can aid in design principles for generating robust and highly-stable mode-locked pulses. Full article

(This article belongs to the Special Issue Nonlinear Fiber Optics)

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1188 KiB

Open AccessArticle

Dynamics of a Dispersion-Managed Passively Mode-Locked Er-Doped Fiber Laser Using Single Wall Carbon Nanotubes

by Norihiko Nishizawa, Lei Jin, Hiromichi Kataura and Youichi Sakakibara

Photonics 2015, 2(3), 808-824; https://doi.org/10.3390/photonics2030808 - 21 Jul 2015

Cited by 16 | Viewed by 6840

Abstract

We investigated the dynamics of a dispersion-managed, passively mode-locked, ultrashort-pulse, Er-doped fiber laser using a single-wall carbon nanotube (SWNT) device. A numerical model was constructed for analysis of the SWNT fiber laser. The initial process of passive mode-locking, the characteristics of the output [...] Read more.

We investigated the dynamics of a dispersion-managed, passively mode-locked, ultrashort-pulse, Er-doped fiber laser using a single-wall carbon nanotube (SWNT) device. A numerical model was constructed for analysis of the SWNT fiber laser. The initial process of passive mode-locking, the characteristics of the output pulse, and the dynamics inside the cavity were investigated numerically for soliton, dissipative-soliton, and stretched-pulse mode-locking conditions. The dependencies on the total dispersion and recovery time of the SWNTs were also examined. Numerical results showed similar behavior to experimental results. Full article

(This article belongs to the Special Issue Nonlinear Fiber Optics)

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532 KiB

Open AccessArticle

Multi-Format Wavelength Conversion Using Quantum Dash Mode-Locked Laser Pumps

by Yousra Ben M’Sallem, Chul Soo Park, Sophie LaRochelle and Leslie A. Rusch

Photonics 2015, 2(2), 527-539; https://doi.org/10.3390/photonics2020527 - 14 May 2015

Cited by 5 | Viewed by 4556

Abstract

We investigate and compare the performance of wavelength conversion for two different non-return-to-zero (NRZ) modulation formats at 40 Gb/s: on off keying (OOK) and differential phase-shift keying (DPSK). To achieve wide wavelength coverage and integrability, we use a dual pump scheme exploiting four-wave [...] Read more.

We investigate and compare the performance of wavelength conversion for two different non-return-to-zero (NRZ) modulation formats at 40 Gb/s: on off keying (OOK) and differential phase-shift keying (DPSK). To achieve wide wavelength coverage and integrability, we use a dual pump scheme exploiting four-wave mixing in semiconductor optical amplifiers. For phase stability, we use a quantum-dash mode-locked laser (QD-MLL) as a multi-wavelength source for the dual pumps, with tunability provided by the output filter. The significant sidelobes of the DPSK spectrum (relative to OOK) require the balancing of the pump proximity to the original signal (facilitating high conversion efficiency) with the signal degradation from the pump spectrum overlapping the converted DPSK signal. We achieve a conversion efficiency near –3.6 dB for OOK and –5.4 dB for DPSK across a 12 nm tuning range with low input powers (1 dBm). We measure bit error rate (BER) and obtain error free transmission (BER < 10⁻⁹) with a power penalty less than 2 dB for OOK and 3 dB for DPSK. Full article

(This article belongs to the Special Issue Nonlinear Fiber Optics)

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552 KiB

Open AccessArticle

Performance Analysis of a Hybrid Raman Optical Parametric Amplifier in the O- and E-Bands for CWDM PONs

by Sasanthi Peiris, Nicholas Madamopoulos, Neophytos A. Antoniades, Dwight Richards and Roger Dorsinville

Photonics 2014, 1(4), 473-487; https://doi.org/10.3390/photonics1040473 - 01 Dec 2014

Cited by 2 | Viewed by 5355

Abstract

We describe a hybrid Raman-optical parametric amplifier (HROPA) operating at the O- and E-bands and designed for coarse wavelength division multiplexed (CWDM) passive optical networks (PONs). We present the mathematical model and simulation results for the optimization of this HROPA design. Our analysis [...] Read more.

We describe a hybrid Raman-optical parametric amplifier (HROPA) operating at the O- and E-bands and designed for coarse wavelength division multiplexed (CWDM) passive optical networks (PONs). We present the mathematical model and simulation results for the optimization of this HROPA design. Our analysis shows that separating the two amplification processes allows for optimization of each one separately, e.g., proper selection of pump optical powers and wavelengths to achieve maximum gain bandwidth and low gain ripple. Furthermore, we show that the proper design of optical filters incorporated in the HROPA architecture can suppress idlers generated during the OPA process, as well as other crosstalk that leaks through the passive optical components. The design approach enables error free performance for all nine wavelengths within the low half of the CWDM band, assigned to upstream traffic in a CWDM PON architecture, for all possible transmitter wavelength misalignments (±6 nm) from the center wavelength of the channel band. We show that the HROPA can achieve error-free performance with a 170-nm gain bandwidth (e.g., 1264 nm–1436 nm), a gain of >20 dB and a gain ripple of <4 dB. Full article

(This article belongs to the Special Issue Nonlinear Fiber Optics)

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561 KiB

Open AccessArticle

Effects of Temperature and Axial Strain on Four-Wave Mixing Parametric Frequencies in Microstructured Optical Fibers Pumped in the Normal Dispersion Regime

by Javier Abreu-Afonso, Antonio Díez, Jose Luis Cruz and Miguel V. Andrés

Photonics 2014, 1(4), 404-411; https://doi.org/10.3390/photonics1040404 - 29 Oct 2014

Cited by 7 | Viewed by 4806

Abstract

A study of the effect of temperature and axial strain on the parametric wavelengths produced by four-wave mixing in microstructured optical fibers is presented. Degenerate four-wave mixing was generated in the fibers by pumping at normal dispersion, near the zero-dispersion wavelength, causing the [...] Read more.

A study of the effect of temperature and axial strain on the parametric wavelengths produced by four-wave mixing in microstructured optical fibers is presented. Degenerate four-wave mixing was generated in the fibers by pumping at normal dispersion, near the zero-dispersion wavelength, causing the appearance of two widely-spaced four-wave mixing spectral bands. Temperature changes, and/or axial strain applied to the fiber, affects the dispersion characteristics of the fiber, which can result in the shift of the parametric wavelengths. We show that the increase of temperature causes the signal and idler wavelengths to shift linearly towards shorter and longer wavelengths, respectively. For the specific fiber of the experiment, the band shift at rates –0.04 nm/ºC and 0.3 nm/ºC, respectively. Strain causes the parametric bands to shift in the opposite way. The signal band shifted 2.8 nm/me and the idler -5.4 nm/me. Experimental observations are backed by numerical simulations. Full article

(This article belongs to the Special Issue Nonlinear Fiber Optics)

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1972 KiB

Open AccessArticle

Asymmetric Wave Propagation Through Saturable Nonlinear Oligomers

by Daniel Law, Jennie D'Ambroise, Panayotis G. Kevrekidis and Detlef Kip

Photonics 2014, 1(4), 390-403; https://doi.org/10.3390/photonics1040390 - 27 Oct 2014

Cited by 6 | Viewed by 4405

Abstract

In the present paper we consider nonlinear dimers and trimers (more generally, oligomers) embedded within a linear Schrödinger lattice where the nonlinear sites are of saturable type. We examine the stationary states of such chains in the form of plane waves, and analytically [...] Read more.

In the present paper we consider nonlinear dimers and trimers (more generally, oligomers) embedded within a linear Schrödinger lattice where the nonlinear sites are of saturable type. We examine the stationary states of such chains in the form of plane waves, and analytically compute their reflection and transmission coefficients through the nonlinear oligomer, as well as the corresponding rectification factors which clearly illustrate the asymmetry between left and right propagation in such systems. We examine not only the existence but also the dynamical stability of the plane wave states. Lastly, we generalize our numerical considerations to the more physically relevant case of Gaussian initial wavepackets and confirm that the asymmetry in the transmission properties also persists in the case of such wavepackets. Full article

(This article belongs to the Special Issue Nonlinear Fiber Optics)

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Review

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925 KiB

Open AccessReview

Sensitivity Enhancement for Fiber Bragg Grating Sensors by Four Wave Mixing

by Jiangbing Du, Lu Li, Xinyu Fan, Qingwen Liu and Zuyuan He

Photonics 2015, 2(2), 426-439; https://doi.org/10.3390/photonics2020426 - 16 Apr 2015

Cited by 11 | Viewed by 6161

Abstract

All-optical signal processing based on four wave mixing (FWM) in a highly nonlinear fiber (HNLF) to enhance the sensitivity of a fiber sensor is demonstrated and comprehensively reviewed in this paper. The principle is based on the frequency chirp magnification (FCM) by FWM. [...] Read more.

All-optical signal processing based on four wave mixing (FWM) in a highly nonlinear fiber (HNLF) to enhance the sensitivity of a fiber sensor is demonstrated and comprehensively reviewed in this paper. The principle is based on the frequency chirp magnification (FCM) by FWM. Degenerated FWM, cascaded two-stage FWM and pump-pulsed FWM with optical parametric amplification (OPA) are experimentally utilized for magnifying the frequency chirp. By using the pump pulse modulation to increase the peak power, OPA can be induced with the use of a dispersion-optimized HNLF. Therefore, ultra-highly efficient FWM can be realized due to the high peak power and OPA. By using the fiber Bragg grating (FBG) laser as the FWM pump, the wavelength drift of the FBG can thus be magnified due to the FCM. We obtain a sensing performance of 13.3 pm/με strain sensitivity and 141.2 pm/°C temperature sensitivity for a conventional FBG, which has an intrinsic strain sensitivity of only ~1 pm/με and an intrinsic temperature sensitivity of only ~10 pm/°C, respectively. Full article

(This article belongs to the Special Issue Nonlinear Fiber Optics)

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843 KiB

Open AccessReview

All Optical Signal-Processing Techniques Utilizing Four Wave Mixing

by Refat Kibria and Michael W. Austin

Photonics 2015, 2(1), 200-213; https://doi.org/10.3390/photonics2010200 - 10 Feb 2015

Cited by 14 | Viewed by 6755

Abstract

Four Wave Mixing (FWM) based optical signal-processing techniques are reviewed. The use of FWM in arithmetical operation like subtraction, wavelength conversion and pattern recognition are three key parts discussed in this paper after a brief introduction on FWM and its comparison with other [...] Read more.

Four Wave Mixing (FWM) based optical signal-processing techniques are reviewed. The use of FWM in arithmetical operation like subtraction, wavelength conversion and pattern recognition are three key parts discussed in this paper after a brief introduction on FWM and its comparison with other nonlinear mixings. Two different approaches to achieve correlation are discussed, as well as a novel technique to realize all optical subtraction of two optical signals. Full article

(This article belongs to the Special Issue Nonlinear Fiber Optics)

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