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High Power Tm3+-Doped Fiber Lasers Tuned by a Variable Reflective Output CouplerEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Wide wavelength tuning by a variable reflective output coupler is demonstrated in high-power double-clad Tm3+-doped silica fiber lasers diode-pumped at ∼790 nm. Varying the output coupling from 96% to 5%, the laser wavelength is tuned over a range of 106 nm from 1949 to 2055 nm. The output power exceeds 20 W over 90-nm range and the maximum output power is 32 W at 1949 nm for 51-W launched pump power, corresponding to a slope efficiency of ∼70%. Assisted with different fiber lengths, the tuning range is expanded to 240 nm from 1866 to 2107&#x...
Source: Research Letters in Optics - November 5, 2009 Category: Physics Source Type: journals

Using Nonuniform Fiber to Generate Slow Light via SBSEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The data pulse delay based on slow light induced by stimulated Brillouin scattering (SBS) in a nonuniform dispersion decreasing fiber (DDF) is demonstrated experimentally, and the distortions of data pulses at different beat frequencies are studied. We found that a delay exceeding a pulse width can be achieved at particular beat frequency, and the DDF has larger delay versus gain slope coefficient with much better output pulse quality than single-mode fiber. (Source: Research Letters in Optics)
Source: Research Letters in Optics - November 5, 2009 Category: Physics Source Type: journals

Influence of Even-Order Dispersion on Super-Sech Soliton Transmission Quality under Coherent CrosstalkEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The transmission speed of optical network strongly depends on the impact of higher order dispersion. In presence of coherent crosstalk, which cannot be otherwise controlled by optical filtering, the impact of higher order dispersions becomes more pronounced. In this paper, the general expressions, that describe pulse deformation due to second- and fourth-order dispersions in a single-mode fiber, are given. The responses for such even-order dispersions, in presence of coherent crosstalk, are characterized by waveforms with long trailing edges. The transmission quality of optical pulses, due to both individual and combined i...
Source: Research Letters in Optics - November 5, 2009 Category: Physics Source Type: journals

The Role of Fermi Resonance in Formation of Valence Band of Water Raman ScatteringEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The role of Fermi resonance in formation of valence band of water Raman scattering was investigated. Simultaneous measurement of characteristics of bending and valence bands of water in D2O solutions, KBr, and KCl and using genetic algorithms in conjunction with variation methods allowed increasing accuracy of estimation of Fermi resonance coupling constant and of Fermi resonance contribution into formation of water Raman valence band. (Source: Research Letters in Optics)
Source: Research Letters in Optics - November 5, 2009 Category: Physics Source Type: journals

High-Power Hybrid Mode-Locked External Cavity Semiconductor Laser Using Tapered Amplifier with Large TunabilityEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We report on hybrid mode-locked laser operation of a tapered semiconductor amplifier in an external ring cavity, generating pulses as short as 0.5 ps at 88.1 MHz with an average power of 60 mW. The mode locking is achieved through a combination of a multiple quantum well saturable absorber (>10% modulation depth) and an RF current modulation. This designed laser has 20 nm tuning bandwidth in continuous wave and 10 nm tuning bandwidth in mode locking around 786 nm center wavelength at constant temperature. (Source: Research Letters in Optics)
Source: Research Letters in Optics - November 5, 2009 Category: Physics Source Type: journals

Analytical Structuring of Periodic and Regular Cascading Solutions in Self-Pulsing LasersEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A newly proposed strong harmonic-expansion method is applied to the laser-Lorenz equations to analytically construct a few typical solutions, including the first few expansions of the well-known period-doubling cascade that characterizes the system in its self-pulsing regime of operation. These solutions are shown to evolve in accordance with the driving frequency of the permanent solution that we recently reported to illustrate the system. The procedure amounts to analytically construct the signal Fourier transform by applying an iterative algorithm that reconstitutes the first few terms of its development. (Source: Resea...
Source: Research Letters in Optics - November 5, 2009 Category: Physics Source Type: journals

Demonstration of an All-Optical 2-to-4 Level Encoder Based on an Optical Parametric AmplifierEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We demonstrated a novel technique for all-optical 2-to-4 level amplitude-shift keying (ASK) coding based on a fiber optical parametric amplifier. A 20-Gb/s signal is realized by multiplexing two 10-Gb/s data streams. (Source: Research Letters in Optics)
Source: Research Letters in Optics - November 5, 2009 Category: Physics Source Type: journals

Single and Multiple Phase Shifts Tilted Fiber Bragg GratingsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The spectral behavior of single and multiple phase shifts tilted fiber Bragg gratings has been experimentally investigated. To this aim, a simple and cost-effective postprocessing technique based on local thermal treatment was used to create arbitrary phase shifts along the tilted grating structure. In particular, UV written tilted fiber Bragg gratings were treated by the electric arc discharge to erase the refractive index modulation in well-defined regions. We demonstrate that these defects give rise to interference pattern for all modes, and thus defect states can be achieved within all the attenuation bands, enabling a...
Source: Research Letters in Optics - November 5, 2009 Category: Physics Source Type: journals

Optimization of Multiple Active Ion Doped Fiber Amplifiers for Three Communication WindowsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present for the first time a theoretical model of Er3+-Tm3+-Pr3+ codoped fiber pumped with both 800 nm and 980 nm lasers to explore possibility of this co-doped system as all-wave fiber amplifier. The rate and power propagation equations of the model are solved numerically and the dependence of the gains at 1310, 1470, 1530, 1600, 1650 nm windows on fiber length is calculated. The results show that with pump power of 200 mW/200 mW, when the concentrations of Pr3+, Tm3+, Er3+ are around 1.7×1024, 3.9×1024, 1.2×1024 (ions/m3), respectively, the signals at 1310, 1470,...
Source: Research Letters in Optics - November 5, 2009 Category: Physics Source Type: journals

Surface Plasmons and Surface Enhanced Raman Spectra of Aggregated and Alloyed Gold-Silver NanoparticlesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Effects of size, morphology, and composition of gold and silver nanoparticles on surface plasmon resonance (SPR) and surface enhanced Raman spectroscopy (SERS) are studied with the purpose of optimizing SERS substrates. Various gold and silver films made by evaporation and subsequent annealing give different morphologies and compositions of nanoparticles and thus different position of the SPR peak. SERS measurements of 4-mercaptobenzoic acid obtained from these films reveal that the proximity of the SPR peak to the exciting laser wavelength is not the only factor leading to the highest Raman enhancement. Silver nanoparticl...
Source: Research Letters in Optics - November 5, 2009 Category: Physics Source Type: journals

Pump Spectral Bandwidth, Birefringence, and Entanglement in Type-II Parametric Down ConversionEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The twin photons produced by a type-II spontaneous parametric down conversion are well know as a potential source of photons for quantum teleportation due to the strong entanglement in polarization. This strong entanglement in polarization, however, depends on the spectral composition of the pump photon and the nature of optical isotropy of the crystal. By exact numerical calculation of the concurrence, we have shown that how pump photons spectral width and the birefringence nature of the crystal directly affect the degree of polarization entanglement of the twin photons. (Source: Research Letters in Optics)
Source: Research Letters in Optics - November 5, 2009 Category: Physics Source Type: journals

A Simple Approach for Enhancing the Output Performance of Solar-Pumped Solid-State LasersEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A simple truncated fused silica elliptical cavity is proposed to enhance the output performance of solar-pumped solid-state lasers. The imaging property of the truncated elliptical cavity ensures an enhanced absorption distribution within an Nd:YAG rod. Optimum pumping parameters are found through ZEMAX nonsequential ray-tracing and LASCAD laser cavity analyses. Compared with the output laser performance of a 3D-compound parabolic concentrator-2D-compound parabolic concentrator (3D-CPC-2D-CPC) cavity, the truncated cavity provides 11% more multimode and 72.7% more TEM00 laser powers. A laser beam of high beam quali...
Source: Research Letters in Optics - November 5, 2009 Category: Physics Source Type: journals

Bayesian Estimation of the Axial Position in Astigmatism-Based Three-Dimensional Particle TrackingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Accurate estimation of the axial position of a molecule using a single lateral image remains a challenge in fluorescent single particle tracking. Here, a principled algorithm for the Bayesian estimation of the axial position of a molecule in three-dimensional astigmatism-based particle tracking is proposed. This technique uses the data from a calibration image set to derive the position without assuming a functional form for the abberated defocusing curve. Using a calibration image set from forty 57 nm beads, the axial position is calculated, and the error associated with position estimation is discussed. This metho...
Source: Research Letters in Optics - November 5, 2009 Category: Physics Source Type: journals

Pump Spectral Bandwidth, Birefringence, and Entanglement in Type-II Parametric Down ConversionEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The twin photons produced by a type-II spontaneous parametric down conversion are well know as a potential source of photons for quantum teleportation due to the strong entanglement in polarization. This strong entanglement in polarization, however, depends on the spectral composition of the pump photon and the nature of optical isotropy of the crystal. By exact numerical calculation of the concurrence, we have shown that how pump photons spectral width and the birefringence nature of the crystal directly affect the degree of polarization entanglement of the twin photons. (Source: Research Letters in Optics)
Source: Research Letters in Optics - July 27, 2009 Category: Physics Source Type: journals

Surface Plasmons and Surface Enhanced Raman Spectra of Aggregated and Alloyed Gold-Silver NanoparticlesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Effects of size, morphology, and composition of gold and silver nanoparticles on surface plasmon resonance (SPR) and surface enhanced Raman spectroscopy (SERS) are studied with the purpose of optimizing SERS substrates. Various gold and silver films made by evaporation and subsequent annealing give different morphologies and compositions of nanoparticles and thus different position of the SPR peak. SERS measurements of 4-mercaptobenzoic acid obtained from these films reveal that the proximity of the SPR peak to the exciting laser wavelength is not the only factor leading to the highest Raman enhancement. Silver nanoparticl...
Source: Research Letters in Optics - July 1, 2009 Category: Physics Source Type: journals

High Power Tm3+-Doped Fiber Lasers Tuned by a Variable Reflective Output CouplerEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Wide wavelength tuning by a variable reflective output coupler is demonstrated in high-power double-clad Tm3+-doped silica fiber lasers diode-pumped at ∼790 nm. Varying the output coupling from 96% to 5%, the laser wavelength is tuned over a range of 106 nm from 1949 to 2055 nm. The output power exceeds 20 W over 90-nm range and the maximum output power is 32 W at 1949 nm for 51-W launched pump power, corresponding to a slope efficiency of ∼70%. Assisted with different fiber lengths, the tuning range is expanded to 240 nm from 1866 to 2107&#x...
Source: Research Letters in Optics - June 10, 2009 Category: Physics Source Type: journals

Using Nonuniform Fiber to Generate Slow Light via SBSEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The data pulse delay based on slow light induced by stimulated Brillouin scattering (SBS) in a nonuniform dispersion decreasing fiber (DDF) is demonstrated experimentally, and the distortions of data pulses at different beat frequencies are studied. We found that a delay exceeding a pulse width can be achieved at particular beat frequency, and the DDF has larger delay versus gain slope coefficient with much better output pulse quality than single-mode fiber. (Source: Research Letters in Optics)
Source: Research Letters in Optics - June 10, 2009 Category: Physics Source Type: journals

Influence of Even-Order Dispersion on Super-Sech Soliton Transmission Quality under Coherent CrosstalkEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The transmission speed of optical network strongly depends on the impact of higher order dispersion. In presence of coherent crosstalk, which cannot be otherwise controlled by optical filtering, the impact of higher order dispersions becomes more pronounced. In this paper, the general expressions, that describe pulse deformation due to second- and fourth-order dispersions in a single-mode fiber, are given. The responses for such even-order dispersions, in presence of coherent crosstalk, are characterized by waveforms with long trailing edges. The transmission quality of optical pulses, due to both individual and combined i...
Source: Research Letters in Optics - June 10, 2009 Category: Physics Source Type: journals

The Role of Fermi Resonance in Formation of Valence Band of Water Raman ScatteringEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The role of Fermi resonance in formation of valence band of water Raman scattering was investigated. Simultaneous measurement of characteristics of bending and valence bands of water in D2O solutions, KBr, and KCl and using genetic algorithms in conjunction with variation methods allowed increasing accuracy of estimation of Fermi resonance coupling constant and of Fermi resonance contribution into formation of water Raman valence band. (Source: Research Letters in Optics)
Source: Research Letters in Optics - June 10, 2009 Category: Physics Source Type: journals

High-Power Hybrid Mode-Locked External Cavity Semiconductor Laser Using Tapered Amplifier with Large TunabilityEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We report on hybrid mode-locked laser operation of a tapered semiconductor amplifier in an external ring cavity, generating pulses as short as 0.5 ps at 88.1 MHz with an average power of 60 mW. The mode locking is achieved through a combination of a multiple quantum well saturable absorber (>10% modulation depth) and an RF current modulation. This designed laser has 20 nm tuning bandwidth in continuous wave and 10 nm tuning bandwidth in mode locking around 786 nm center wavelength at constant temperature. (Source: Research Letters in Optics)
Source: Research Letters in Optics - June 10, 2009 Category: Physics Source Type: journals

Analytical Structuring of Periodic and Regular Cascading Solutions in Self-Pulsing LasersEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A newly proposed strong harmonic-expansion method is applied to the laser-Lorenz equations to analytically construct a few typical solutions, including the first few expansions of the well-known period-doubling cascade that characterizes the system in its self-pulsing regime of operation. These solutions are shown to evolve in accordance with the driving frequency of the permanent solution that we recently reported to illustrate the system. The procedure amounts to analytically construct the signal Fourier transform by applying an iterative algorithm that reconstitutes the first few terms of its development. (Source: Resea...
Source: Research Letters in Optics - June 10, 2009 Category: Physics Source Type: journals

Demonstration of an All-Optical 2-to-4 Level Encoder Based on an Optical Parametric AmplifierEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We demonstrated a novel technique for all-optical 2-to-4 level amplitude-shift keying (ASK) coding based on a fiber optical parametric amplifier. A 20-Gb/s signal is realized by multiplexing two 10-Gb/s data streams. (Source: Research Letters in Optics)
Source: Research Letters in Optics - June 10, 2009 Category: Physics Source Type: journals

Single and Multiple Phase Shifts Tilted Fiber Bragg GratingsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The spectral behavior of single and multiple phase shifts tilted fiber Bragg gratings has been experimentally investigated. To this aim, a simple and cost-effective postprocessing technique based on local thermal treatment was used to create arbitrary phase shifts along the tilted grating structure. In particular, UV written tilted fiber Bragg gratings were treated by the electric arc discharge to erase the refractive index modulation in well-defined regions. We demonstrate that these defects give rise to interference pattern for all modes, and thus defect states can be achieved within all the attenuation bands, enabling a...
Source: Research Letters in Optics - June 10, 2009 Category: Physics Source Type: journals

Optimization of Multiple Active Ion Doped Fiber Amplifiers for Three Communication WindowsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present for the first time a theoretical model of Er3+-Tm3+-Pr3+ codoped fiber pumped with both 800 nm and 980 nm lasers to explore possibility of this co-doped system as all-wave fiber amplifier. The rate and power propagation equations of the model are solved numerically and the dependence of the gains at 1310, 1470, 1530, 1600, 1650 nm windows on fiber length is calculated. The results show that with pump power of 200 mW/200 mW, when the concentrations of Pr3+, Tm3+, Er3+ are around 1.7×1024, 3.9×1024, 1.2×1024 (ions/m3), respectively, the signals at 1310, 1470,...
Source: Research Letters in Optics - June 10, 2009 Category: Physics Source Type: journals

Single and Multiple Phase Shifts Tilted Fiber Bragg GratingsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The spectral behavior of single and multiple phase shifts tilted fiber Bragg gratings has been experimentally investigated. To this aim, a simple and cost-effective postprocessing technique based on local thermal treatment was used to create arbitrary phase shifts along the tilted grating structure. In particular, UV written tilted fiber Bragg gratings were treated by the electric arc discharge to erase the refractive index modulation in well-defined regions. We demonstrate that these defects give rise to interference pattern for all modes, and thus defect states can be achieved within all the attenuation bands, enabling a...
Source: Research Letters in Optics - April 16, 2009 Category: Physics Source Type: journals

Demonstration of an All-Optical 2-to-4 Level Encoder Based on an Optical Parametric AmplifierEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We demonstrated a novel technique for all-optical 2-to-4 level amplitude-shift keying (ASK) coding based on a fiber optical parametric amplifier. A 20-Gb/s signal is realized by multiplexing two 10-Gb/s data streams. (Source: Research Letters in Optics)
Source: Research Letters in Optics - March 29, 2009 Category: Physics Source Type: journals

Analytical Structuring of Periodic and Regular Cascading Solutions in Self-Pulsing LasersEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A newly proposed strong harmonic-expansion method is applied to the laser-Lorenz equations to analytically construct a few typical solutions, including the first few expansions of the well-known period-doubling cascade that characterizes the system in its self-pulsing regime of operation. These solutions are shown to evolve in accordance with the driving frequency of the permanent solution that we recently reported to illustrate the system. The procedure amounts to analytically construct the signal Fourier transform by applying an iterative algorithm that reconstitutes the first few terms of its development. (Source: Resea...
Source: Research Letters in Optics - September 30, 2008 Category: Physics Source Type: journals

High Power Tm3+-Doped Fiber Lasers Tuned by a Variable Reflective Output CouplerEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Wide wavelength tuning by a variable reflective output coupler is demonstrated in high-power double-clad Tm3+-doped silica fiber lasers diode-pumped at ∼790 nm. Varying the output coupling from 96% to 5%, the laser wavelength is tuned over a range of 106 nm from 1949 to 2055 nm. The output power exceeds 20 W over 90-nm range and the maximum output power is 32 W at 1949 nm for 51-W launched pump power, corresponding to a slope efficiency of ∼70%. Assisted with different fiber lengths, the tuning range is expanded to 240 nm from 1866 to 2107&#x...
Source: Research Letters in Optics - July 14, 2008 Category: Physics Source Type: journals

Using Nonuniform Fiber to Generate Slow Light via SBSEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The data pulse delay based on slow light induced by stimulated Brillouin scattering (SBS) in a nonuniform dispersion decreasing fiber (DDF) is demonstrated experimentally, and the distortions of data pulses at different beat frequencies are studied. We found that a delay exceeding a pulse width can be achieved at particular beat frequency, and the DDF has larger delay versus gain slope coefficient with much better output pulse quality than single-mode fiber. (Source: Research Letters in Optics)
Source: Research Letters in Optics - July 14, 2008 Category: Physics Source Type: journals

Influence of Even-Order Dispersion on Super-Sech Soliton Transmission Quality under Coherent CrosstalkEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The transmission speed of optical network strongly depends on the impact of higher order dispersion. In presence of coherent crosstalk, which cannot be otherwise controlled by optical filtering, the impact of higher order dispersions becomes more pronounced. In this paper, the general expressions, that describe pulse deformation due to second- and fourth-order dispersions in a single-mode fiber, are given. The responses for such even-order dispersions, in presence of coherent crosstalk, are characterized by waveforms with long trailing edges. The transmission quality of optical pulses, due to both individual and combined i...
Source: Research Letters in Optics - July 14, 2008 Category: Physics Source Type: journals

The Role of Fermi Resonance in Formation of Valence Band of Water Raman ScatteringEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The role of Fermi resonance in formation of valence band of water Raman scattering was investigated. Simultaneous measurement of characteristics of bending and valence bands of water in D2O solutions, KBr, and KCl and using genetic algorithms in conjunction with variation methods allowed increasing accuracy of estimation of Fermi resonance coupling constant and of Fermi resonance contribution into formation of water Raman valence band. (Source: Research Letters in Optics)
Source: Research Letters in Optics - July 14, 2008 Category: Physics Source Type: journals

High-Power Hybrid Mode-Locked External Cavity Semiconductor Laser Using Tapered Amplifier with Large TunabilityEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We report on hybrid mode-locked laser operation of a tapered semiconductor amplifier in an external ring cavity, generating pulses as short as 0.5 ps at 88.1 MHz with an average power of 60 mW. The mode locking is achieved through a combination of a multiple quantum well saturable absorber (>10% modulation depth) and an RF current modulation. This designed laser has 20 nm tuning bandwidth in continuous wave and 10 nm tuning bandwidth in mode locking around 786 nm center wavelength at constant temperature. (Source: Research Letters in Optics)
Source: Research Letters in Optics - July 14, 2008 Category: Physics Source Type: journals