Showing papers on "Laser linewidth published in 2006"
TL;DR: In this paper, the linewidth of a series of Permalloy films with thicknesses of 50 and 100nm was measured using linear function of frequency, with a slope that corresponds to a nominal Landau-Lifshitz phenomenological damping parameter α value of 0.007 and zero frequency intercepts in the 160-320A∕m (2-4Oe) range.
Abstract: Stripline (SL), vector network analyzer (VNA), and pulsed inductive microwave magnetometer (PIMM) techniques were used to measure the ferromagnetic resonance (FMR) linewidth for a series of Permalloy films with thicknesses of 50 and 100nm. The SL-FMR measurements were made for fixed frequencies from 1.5to5.5GHz. The VNA-FMR and PIMM measurements were made for fixed in-plane fields from 1.6to8kA∕m (20–100Oe). The results provide a confirmation, lacking until now, that the linewidths measured by these three methods are consistent and compatible. In the field format, the linewidths are a linear function of frequency, with a slope that corresponds to a nominal Landau-Lifshitz phenomenological damping parameter α value of 0.007 and zero frequency intercepts in the 160–320A∕m (2–4Oe) range. In the frequency format, the corresponding linewidth versus frequency response shows a weak upward curvature at the lowest measurement frequencies and a leveling off at high frequencies.
490 citations
Journal Article•
TL;DR: In this article, the linewidth of a series of Permalloy films with thicknesses of 50 and 100nm was measured using linear function of frequency, with a slope that corresponds to a nominal Landau-Lifshitz phenomenological damping parameter α value of 0.007 and zero frequency intercepts in the 160-320A∕m (2-4Oe) range.
Abstract: Stripline (SL), vector network analyzer (VNA), and pulsed inductive microwave magnetometer (PIMM) techniques were used to measure the ferromagnetic resonance (FMR) linewidth for a series of Permalloy films with thicknesses of 50 and 100nm. The SL-FMR measurements were made for fixed frequencies from 1.5to5.5GHz. The VNA-FMR and PIMM measurements were made for fixed in-plane fields from 1.6to8kA∕m (20–100Oe). The results provide a confirmation, lacking until now, that the linewidths measured by these three methods are consistent and compatible. In the field format, the linewidths are a linear function of frequency, with a slope that corresponds to a nominal Landau-Lifshitz phenomenological damping parameter α value of 0.007 and zero frequency intercepts in the 160–320A∕m (2–4Oe) range. In the frequency format, the corresponding linewidth versus frequency response shows a weak upward curvature at the lowest measurement frequencies and a leveling off at high frequencies.
430 citations
TL;DR: A high spectral resolution, 2D nanohole-array-based surface plasmon resonance sensor that operates at normal or near normal incidence--facilitating high spatial resolution imaging--is presented and the potential of this system of O(10(-6)) RIU under optimal conditions is estimated.
Abstract: A high spectral resolution, 2D nanohole-array-based surface plasmon resonance sensor that operates at normal or near normal incidence--facilitating high spatial resolution imaging--is presented. The angular and spectral transmittance of the structure is modified from a Fano type to a pure Lorentzian line shape with a parallel and orthogonal polarizer-analyzer pair. This change leads to a linewidth narrowing that maximizes the sensor resolution, which we show to be of O(10−5) refractive index units (RIU). We estimate the potential of this system of O(10−6) RIU under optimal conditions.
320 citations
TL;DR: In this paper, an all-fiber high-power single-frequency Brillouin fiber ring laser with maximum power of 100 mW at 1.55 mum was demonstrated, which was actively stabilized by using the Pound-Drever-Hall frequency-locking scheme.
Abstract: We demonstrate an all-fiber high-power single-frequency Brillouin fiber ring laser with maximum power of 100 mW at 1.55 mum, which is actively stabilized by using the Pound-Drever-Hall frequency-locking scheme. Significant reduction (~20dB) of both relative intensity noise and frequency noise was observed in the Brillouin Stokes radiation as compared with those noises of its pump source, a narrow-linewidth Er-doped fiber laser. Ultranarrow spectral linewidth of the Brillouin fiber lasers was investigated by both delayed self-heterodyne technique and heterodyne beat technique between two independent Brillouin fiber lasers
177 citations
TL;DR: In this paper, the performance of an Yb-doped, 100μm core rod-like photonic crystal fiber (PCF) used as the final amplifier in a gain-staged master-oscillator/power-amplifier source was reported.
Abstract: The authors report on the performance of an Yb-doped, 100μm core rodlike photonic crystal fiber (PCF) used as the final amplifier in a gain-staged master-oscillator/power-amplifier source. From the PCF, they obtained 1-ns-long pulses of energy in excess of 4.3mJ, peak/average power ∼4.5MW∕42W, and spectral linewidth ∼20GHz. The PCF emitted a beam exhibiting near-Gaussian, single-transverse-mode profile of M2∼1.3.
174 citations
TL;DR: In this article, a single longitudinal mode (SLM) dual-wavelength erbium-doped fiber (EDF) laser based on a simple linear cavity is proposed and demonstrated.
Abstract: A single-longitudinal-mode (SLM) dual-wavelength erbium-doped fiber (EDF) laser based on a simple linear cavity is proposed and demonstrated. The SLM operation is achieved by incorporating a dual-phase-shift fiber grating with two ultranarrow transmission bands. Due to the gain grating produced by spatial hole-burning in the EDF, the proposed linear cavity supports dual-wavelength oscillation at room temperature with a wavelength interval of 27 pm. The laser output is heterodyned on a photodetector and the generated microwave signal has a linewidth <20 kHz without any feedback.
163 citations
TL;DR: In this paper, the authors have implemented a distributed feedback device in a spectrometer for high-resolution gas phase spectroscopy, where the absolute frequency was determined by mixing the radiation from the quantum cascade laser with that from a gas laser.
Abstract: The quantum cascade laser is a powerful, narrow linewidth, and continuous wave source of terahertz radiation. The authors have implemented a distributed feedback device in a spectrometer for high-resolution gas phase spectroscopy. Amplitude as well as frequency modulation schemes have been realized. The absolute frequency was determined by mixing the radiation from the quantum cascade laser with that from a gas laser. The pressure broadening and the pressure shift of a rotational transition of methanol at 2.519THz were measured in order to demonstrate the performance of the spectrometer.
160 citations
TL;DR: In this article, the authors demonstrate a technique to achieve high-precision tuning of photonic crystal nanocavities by atomic force microscope nano-oxidation of the cavity surface.
Abstract: The authors demonstrate a technique to achieve high-precision tuning of photonic crystal nanocavities by atomic force microscope nano-oxidation of the cavity surface. Relative tuning between two nanocavity modes is achieved though careful choice of the oxide pattern, allowing them to restore the spectral degeneracy conditions necessary to create polarization-entangled quantum states. Tuning steps less than the linewidth (1A) of the high quality factor modes are obtained, allowing for virtually continuous tuning ability.
155 citations
TL;DR: In this article, a theoretical and experimental study of the optical gain, refractive index change, and linewidth enhancement factor (LEF) of a p-doped quantum-dot (QD) laser is reported.
Abstract: A theoretical and experimental study of the optical gain, refractive index change, and linewidth enhancement factor (LEF) of a p-doped quantum-dot (QD) laser is reported These parameters are measured by injecting an external pump, which induces cross-gain and cross-phase modulation A comprehensive theoretical model for the optical gain and refractive index change of InAs QD lasers is introduced with the quasi-equilibrium approximation of carrier distribution We use the Gaussian lineshape function for gain change and the confluent hypergeometric function of the first kind for refractive index change, which satisfies the Kramers-Kronig relation We match the experimental data with the theoretical results when the thermal effect is isolated by an additional pulsed current measurement We also calculate theoretically the optical gain, refractive index change, and LEF of an undoped QD laser of the same structure except the absence of p-type doping We show that the differential gain and LEF of the p-doped QD laser are improved compared with those of the undoped QD laser due to the reduced transparency carrier density
147 citations
TL;DR: In this paper, the authors describe the design and operation of a stable narrow-linewidth linearly polarized fiber ring laser using a polarization-maintaining (PM) erbium-doped fiber as a saturable absorber.
Abstract: This paper describes the design and operation of a stable narrow-linewidth linearly polarized fiber ring laser using a polarization-maintaining (PM) erbium-doped fiber as a saturable absorber. The effect of the PM fiber on suppressing mode hopping is experimentally demonstrated and optimum conditions for single-mode operation are identified. Laser output power is /spl sim/ 4.7 mW at 1535 nm for a pump power of 94 mW, the polarization extinction ratio is 24.8 dB, the SNR is larger than 45 dB, the relative intensity noise is below -104 dB/Hz at frequencies above 150 kHz, and the linewidth is less than 1.5 kHz. Potential applications of the fiber laser for interferometric or spectroscopic fiber sensors are briefly discussed.
141 citations
TL;DR: This work presents the most precise study to date of the 1S0-3P0 optical clock transition with a detailed analysis of systematic shifts in the absolute frequency measurement of 429 228 004 229 869 Hz.
Abstract: With ultracold 87Srconfined in a magic wavelength optical lattice, we present the most precise study (2.8 Hz statistical uncertainty) to date of the 1S0-3P0 optical clock transition with a detailed analysis of systematic shifts (19 Hz uncertainty) in the absolute frequency measurement of 429 228 004 229 869 Hz. The high resolution permits an investigation of the optical lattice motional sideband structure. The local oscillator for this optical atomic clock is a stable diode laser with its hertz-level linewidth characterized by an octave-spanning femtosecond frequency comb.
TL;DR: An ultranarrow-linewidth laser spectrometer at 657 nm, consisting of a diode laser locked in a single stage to a stable high-finesse reference cavity, is reported, characterized by comparison with a second independent system.
Abstract: We report an ultranarrow-linewidth laser spectrometer at 657 nm, consisting of a diode laser locked in a single stage to a stable high-finesse reference cavity. The system is characterized by comparison with a second independent system. From beat frequency measurements a linewidth below 1.5 Hz (FWHM) and a fractional instability of less than 2×10−15 for 1 s of averaging time are observed.
TL;DR: The analysis shows that the disorder due to surface imperfections and finite temperature effects, as well as the relaxation within the fine structure, can have significant impact on the steady-state absorption spectrum, 3PEPS data, and dephasing processes.
Abstract: We study the origin of the spectral line shape in colloidal CdSe nanocrystal quantum dots. The three-pulse photon echo peak shift (3PEPS) data reveal a temperature-independent fast decay, obscuring the quantification of the homogeneous linewidth. The optical gap and Stokes shift are found to have an anomalous behavior with temperature, which is size, capping group, and surrounding polymer matrix independent. Using these results and combining them with simulations, we discuss the role of exciton-phonon coupling, static inhomogeneity, exciton fine structure, and exciton state disorder in the linewidth of the nanocrystal. In particular, our analysis shows that the disorder due to surface imperfections and finite temperature effects, as well as the relaxation within the fine structure, can have significant impact on the steady-state absorption spectrum, 3PEPS data, and dephasing processes.
TL;DR: This is the first example of a single frequency CW SRO pumped by an all-fiber pump source, a reduction in threshold by a factor of three over previous 1- microm-pumpedCW SROs, and a reduction by two orders of magnitude in the linewidth of CW S ROs pumped by fiber pump sources.
Abstract: An oscillation threshold of 780mW has been demonstrated in a singly-resonant, continuous-wave optical parametric oscillator (CW SRO) using a fiber-amplified, distributed feedback (DFB) fiber laser as pump source. A linewidth of 1MHz was measured, and the idler frequency was fine-tuned by up to 130GHz by tuning the pump laser. To our knowledge, this is the first example of a single frequency CW SRO pumped by an all-fiber pump source, a reduction in threshold by a factor of three over previous 1- microm-pumped CW SROs, and a reduction by two orders of magnitude in the linewidth of CW SROs pumped by fiber pump sources.
TL;DR: It is shown that the various techniques commonly used to measure the linewidth enhancement factor can lead to different values when applied to quantum dot semiconductor lasers, a direct consequence of the intrinsic capture/escape dynamics of quantum dot materials and of the free carrier plasma effects.
Abstract: We show that the various techniques commonly used to measure the linewidth enhancement factor can lead to different values when applied to quantum dot semiconductor lasers. Such behaviour is a direct consequence of the intrinsic capture/escape dynamics of quantum dot materials and of the free carrier plasma effects. This provides an explanation for the wide range of values experimentally measured and the linewidth re-broadening recently measured.
TL;DR: In this article, the reference cavity is mounted on four support points in the horizontal symmetry plane of the optical frequency standard and the positions of the points are optimized by finite-element analysis.
Abstract: We report a novel mounting of the reference cavity used for stabilization of the clock laser in an optical frequency standard. The cavity axis is oriented horizontally and the cavity is supported in its horizontal symmetry plane on four support points. The positions of the points were optimized by finite-element analysis. A sensitivity to accelerations of 1.5 kHz/(m/s2) in the vertical and 14 kHz/(m/s2) in the horizontal direction was measured, which is a reduction in the vertical sensitivity by two orders of magnitude compared to the usual support from below.
TL;DR: The results indicate that increasing the spectral linewidth of the pump can decrease the supercontinuum spectral width, and using a fiber with smaller dispersion at the pump wavelength reduces the required fiber length by decreasing the temporal width of the solitons formed from modulation instability.
Abstract: We numerically investigate supercontinuum generation using continuous-wave pumping. It is found that energy transfer during collision of solitons plays an important role. The relative influence of Raman gain on spectral broadening is shown to depend on the width of the calculation time window. Our results indicate that increasing the spectral linewidth of the pump can decrease the supercontinuum spectral width. Using a fiber with smaller dispersion at the pump wavelength reduces the required fiber length by decreasing the temporal width of the solitons formed from modulation instability. This also reduces the sensitivity to the pump spectral linewidth.
TL;DR: In this article, the Sb 4d and S 2p spectra have been fitted to two and three doublets respectively, and the linewidth for all peaks is 0.53 eV.
TL;DR: In this article, a detailed study of the factors determining the linewidth (and hence resolution) in 1H solid-state magic-angle spinning NMR is described, using recently developed, highly efficient methods of numerical simulation, together with experimental measurements on a variety of test systems, they propose a comprehensive picture of 1H resolution under MAS.
Abstract: A detailed study of the factors determining the linewidth (and hence resolution) in 1H solid-state magic-angle spinning NMR is described. Although it has been known from the early days of magic-angle spinning (MAS) that resolution of spectra from abundant nuclear spins, such as 1H, increases approximately linearly with increasing sample rotation rate, the difficulty of describing the dynamics of extended networks of coupled spins has made it difficult to predict a priori the resolution expected for a given sample. Using recently developed, highly efficient methods of numerical simulation, together with experimental measurements on a variety of test systems, we propose a comprehensive picture of 1H resolution under MAS. The "homogeneous" component of the linewidth is shown to depend primarily on the ratio between an effective local coupling strength and the spin rate, modified by geometrical factors which loosely correspond to the "dimensionality" of the coupling network. The remaining "inhomogeneous" component of the natural linewidth is confirmed to have the same properties as in dilute-spin NMR. Variations in the NMR frequency due to chemical shift effects are shown to have minimal impact on 1H resolution. The implications of these results for solid-state NMR experiments involving 1H and other abundant-spin nuclei are discussed.
TL;DR: In this paper, a continuously tunable optofluidic distributed feedback (DFB) dye laser was demonstrated on a monolithic replica molded poly(dimethylsiloxane) (PDMS) chip.
Abstract: A continuously tunable optofluidic distributed feedback (DFB) dye laser was demonstrated on a monolithic replica molded poly(dimethylsiloxane) (PDMS) chip. The optical feedback was provided by a phase-shifted higher order Bragg grating embedded in the liquid core of a single mode buried channel waveguide. Due to the soft elastomeric nature of PDMS, the laser frequency could be tuned by mechanically stretching the grating period. In principle, the mechanical tuning range is only limited by the gain bandwidth. A tuning range of nearly 60nm was demonstrated from a single dye laser chip by combining two common dye molecules Rhodamine 6G and Rhodamine 101. Single-mode operation was maintained with less than 0.1nm linewidth. Because of the higher order grating, a single laser, when operated with different dye solutions, can provide tunable light output covering the entire spectrum from near UV to near IR in which efficient laser dyes are available. An array of five DFB dye lasers with different grating periods was also demonstrated on a chip. Such tunable integrated laser arrays are expected to become key components in inexpensive advanced spectroscopy chips.
TL;DR: In this article, the authors performed detailed studies of state-of-the-art laser stabilization to high finesse optical cavities, revealing fundamental mechanical thermal noise-related length fluctuations.
Abstract: We perform detailed studies of state-of-the-art laser stabilization to high finesse optical cavities, revealing fundamental mechanical thermal noise-related length fluctuations. We compare the frequency noise of lasers tightly locked to the resonances of a variety of rigid Fabry-Perot cavities of differing lengths and mirror substrate materials. The results are in agreement with the theoretical model proposed in K. Numata, A. Kemery, and J. Camp [Phys. Rev. Lett. 93, 250602 (2004)]. The results presented here on the fundamental limits of FP references will impact planning and construction of next generation ultrastable optical cavities.
HGST1
TL;DR: In this article, the current and temperature dependences of the microwave voltage emission of spin-valve nanopillars subjected to an in-plane magnetic field and a perpendicular-to-plane current were studied.
Abstract: We study the current and temperature dependences of the microwave voltage emission of spin-valve nanopillars subjected to an in-plane magnetic field and a perpendicular-to-plane current. Despite the complex multilayer geometry, clear microwave emission is observed for current densities in the interval of 9×107–13×107Acm−2. The emission frequency stays near 12GHz when I
TL;DR: A monolithic integrated Raman silicon laser based on silicon-on-insulator (SOI) rib waveguide race-track ring resonator with an integrated p-i-n diode structure to provide a highly integrated and scaleable monolithic device.
Abstract: We present a monolithic integrated Raman silicon laser based on silicon-on-insulator (SOI) rib waveguide race-track ring resonator with an integrated p-i-n diode structure. Under reverse biasing, we achieved stable, single mode, continuous-wave (CW) lasing with output power exceeding 30mW and 10% slope efficiency. The laser emission has high spectral purity with a measured side mode suppression exceeding 70dB and laser linewidth of <100 kHz. This laser architecture allows for on-chip integration with other silicon photonics components to provide a highly integrated and scaleable monolithic device.
TL;DR: In this article, a detailed experimental study of the oscillation frequency, linewidth, RF spectrum and the phase noise of a radiation-pressure-driven micromechanical oscillator in a microtoroid geometry is presented.
Abstract: We present for the first time a detailed experimental study of the oscillation frequency, linewidth, RF spectrum and the phase noise of a radiation-pressure-driven micromechanical oscillator in a microtoroid geometry. Through this study we identify the critical parameters for optimal operation of this device and derive key expressions for tailoring the desired characteristics. The outcome of this study paves the ground for exploiting this unique phenomenon in photonic systems as well as fundamental studies in macroscopic quantum mechanics.
TL;DR: A linearly polarized, narrow-linewidth, diode-pumped, Yb-doped silica-fiber oscillator operating at 1150 nm was frequency doubled to produce 40 mW of 575 nm radiation.
Abstract: A linearly polarized, narrow-linewidth, diode-pumped, Yb-doped silica-fiber oscillator operating at 1150 nm was frequency doubled to produce 40 mW of 575 nm radiation. The oscillator generated 89 mW of cw linearly polarized output power and was tunable over 0.80 nm. The laser output was coupled to a periodically poled LiNbO3 waveguide that converted 67% of the coupled power to the yellow. The system was fully integrated, with no free-space optics, and had an overall optical-to-optical efficiency of 7.0% with respect to the incident diode-laser pump power.
TL;DR: In this article, the authors demonstrate passive mode locking in one-section monolithic semiconductor laser diodes based on quantum-dash active layer at very high repetition rate in the 1.5μm window.
Abstract: We demonstrate passive mode locking in one-section monolithic semiconductor laser diodes based on quantum-dash active layer at very high repetition rate in the 1.5μm window. Transform-limited pulses are generated at 134GHz with subpicosecond width, without any pulse compression scheme. A 50kHz linewidth of the radio-frequency spectrum is also demonstrated at 42GHz, the lowest value reported for any passively mode-locked semiconductor laser. We further show that the saturable absorption section in two-section devices has no significant impact on the mode-locking behavior.
TL;DR: The delayed self-heterodyne interferometric technique, first proposed in the context of semiconductor lasers, has been commonly used for over 20 years in the determination of the optical linewidth of lasers.
Abstract: The delayed self-heterodyne interferometric technique, first proposed in the context of semiconductor lasers, has been commonly used for over 20 years in the determination of the optical linewidth of lasers. We examine this technique in the light of recent work on fiber lasers, and point out further constraints in the applicability of these measurements. An approximate but simple and intuitive expression is provided for assessing the self-heterodyne technique when applied to fiber lasers.
TL;DR: An integrated semiconductor source of counterpropagating twin photons in the telecom range is experimentally demonstrated, opening a route towards new guided-wave semiconductor quantum devices.
Abstract: We experimentally demonstrate an integrated semiconductor source of counterpropagating twin photons in the telecom range. A pump beam impinging on top of an AlGaAs waveguide generates parametrically two counterpropagating, orthogonally polarized signal/idler guided modes. A 2 mm long waveguide emits at room temperature one average photon pair per pump pulse, with a spectral linewidth of 0.15 nm. The twin character of the emitted photons is ascertained through a time-correlation measurement. This work opens a route towards new guided-wave semiconductor quantum devices.
Patent•
26 Jan 2006
TL;DR: In this article, an approach for spectral-beam combining light from a plurality of high-power fiber lasers that use two substantially identical diffraction gratings in a parallel, mutually compensating configuration is presented.
Abstract: Apparatus and method for spectral-beam combining light from a plurality of high-power fiber lasers that, in some embodiments, use two substantially identical diffraction gratings in a parallel, mutually compensating configuration to combine a plurality of separate parallel input beams each having a slightly different successively higher wavelength into a single output beam of high quality. In other embodiments, a single diffraction grating is used to combine a plurality of different wavelengths, wherein the input laser beams are obtained from very narrow linewidth sources to reduce chromatic dispersion. In some embodiments, diagnostics and adjustments of wavelengths and/or positions and angles are made dynamically in real time to maintain the combination of the plurality input beams into a single high-quality output beam.
TL;DR: A quasi-continuous wave Dy3+-doped ZBLAN fibre laser pumped by a ~1.3 μm Nd:YAG laser and operating at 2.96 μm with an emission linewidth of ~14 nm (FWHM) has been demonstrated.
Abstract: A quasi-continuous wave Dy3+-doped ZBLAN fibre laser pumped by a ~1.3 μm Nd:YAG laser and operating at 2.96 μm with an emission linewidth of ~14 nm (FWHM) has been demonstrated. The 6H15/2 → 6H9/2 , 6F11/2 absorption band of Dy3+-doped ZBLAN centred at 1.3 μm has been used to pump the 6H13/2 → 6H15/2 laser transition. For a 60 cm fibre length, a threshold of 0.5 W and a slope efficiency of ~20% with respect to the absorbed pump power was measured. The experimental slope efficiency was ~45% of the Stokes efficiency limit. The high efficiency relates to low pump ESA losses and an optimised output coupling as compared with previous demonstrations.