Showing papers on "Tunable laser published in 2010"
TL;DR: In this article, the authors demonstrate room-temperature pulsed laser emission from optically pumped metallo-dielectric cavities that are smaller than their emission wavelength in all three dimensions.
Abstract: We demonstrate room-temperature pulsed laser emission from optically pumped metallo-dielectric cavities that are smaller than their emission wavelength in all three dimensions. The cavity consists of an aluminium/silica bi-layer shield surrounding an InGaAsP disk in which the thickness of the silica layer is optimized to minimize the gain threshold of the laser. The lasers are pumped using a 1,064-nm pulsed fibre laser with a pulse width of 12 ns and repetition rate of 300 kHz. Lasing emission at 1.43 µm is observed from a laser with slightly elliptical gain core with major and minor diameters of 490 and 420 nm, respectively. Owing to the isolation provided by the aluminium shield, this laser design approach can be used to create arrays of uncoupled lasers with emitter densities that are close to the Rayleigh resolution limit. Room-temperature lasing from metallo-dielectric cavities that are smaller than their emission wavelength in all three dimensions is reported. The cavity consists of an aluminium/silica bi-layer shield that surrounds an InGaAsP disk. The gain threshold of the laser is minimized by optimizing the thickness of the silica layer.
501 citations
TL;DR: After the invention of lasers, in the past 50 years progress made in laser-based display technology has been very promising, with commercial products awaiting release to the mass market.
Abstract: After the invention of lasers, in the past 50 years progress made in laser-based display technology has been very promising, with commercial products awaiting release to the mass market. Compact laser systems, such as edge-emitting diodes, vertical-cavity surface-emitting lasers, and optically pumped semiconductor lasers, are suitable candidates for laser-based displays. Laser speckle is an important concern, as it degrades image quality. Typically, one or multiple speckle reduction techniques are employed in laser displays to reduce speckle contrast. Likewise, laser safety issues need to be carefully evaluated in designing laser displays under different usage scenarios. Laser beam shaping using refractive and diffractive components is an integral part of laser displays, and the requirements depend on the source specifications, modulation technique, and the scanning method being employed in the display. A variety of laser-based displays have been reported, and many products such as pico projectors and laser televisions are commercially available already.
330 citations
TL;DR: The progress, and current challenges, in fabricating rare-earth-doped chalcogenide-glass fibers for developing mid-infrared (IR) fiber lasers are reviewed and for the first time a coherent explanation is forwarded for the failure to date to develop a gallium-lanthanum-sulfide glass mid-IR fiber laser.
Abstract: The progress, and current challenges, in fabricating rare-earth-doped chalcogenide-glass fibers for developing mid-infrared (IR) fiber lasers are reviewed. For the first time a coherent explanation is forwarded for the failure to date to develop a gallium-lanthanum-sulfide glass mid-IR fiber laser. For the more covalent chalcogenide glasses, the importance of optimizing the glass host and glass processing routes in order to minimize non-radiative decay and to avoid rare earth ion clustering and glass devitrification is discussed. For the first time a new idea is explored to explain an additional method of non-radiative depopulation of the excited state in the mid-IR that has not been properly recognized before: that of impurity multiphonon relaxation. Practical characterization of candidate selenide glasses is presented. Potential applications of mid-infrared fiber lasers are suggested.
258 citations
TL;DR: In this paper, an all-fiber tunable passively Q-switched erbium-doped fiber (EDF) laser is presented, where saturable absorbers are constructed by optically driven deposition of single-wall carbon nanotubes on fiber connectors.
Abstract: An all-fiber tunable passively Q-switched erbium-doped fiber (EDF) laser is presented. Saturable absorbers are constructed by optically driven deposition of single-wall carbon nanotubes on fiber connectors. A low pump threshold of 11.1 mW is achieved. Self-mode-locking effect is also observed, and it could be suppressed by splicing an extra unpumped EDF into the laser ring cavity. The laser can be tuned by applying axial strain on the fiber Bragg grating which serves as a narrowband external mirror of the cavity.
253 citations
TL;DR: In this paper, the soliton operation and wavelength tuning of erbium-doped fiber laser with atomic layer graphene was investigated under various cavity dispersion conditions, and it was shown that not only wide range soliton wavelength tuning but also soliton pulse width variation could be obtained in the fiber laser.
Abstract: Soliton operation and soliton wavelength tuning of erbium-doped fiber lasers mode locked with atomic layer graphene was experimentally investigated under various cavity dispersion conditions. It was shown that not only wide range soliton wavelength tuning but also soliton pulse width variation could be obtained in the fiber lasers. Our results show that the graphene mode locked erbium-doped fiber lasers provide a compact, user friendly and low cost wavelength tunable ultrashort pulse source.
223 citations
TL;DR: In this paper, transition metal doped II-VI materials and recent progress in Cr- and Fe-doped solid-state mid-IR lasers are reviewed for tunability over 19-51 μm.
Abstract: Recent progress in chromium and iron doped II-VI semiconductor materials makes them the laser sources of choice when one needs a compact system with tunability over 19–51 μm Output powers exceeding 10 W and efficiency up to 70% were demonstrated in several Cr doped semiconductors The unique combination of technological (low-cost ceramic material) and spectroscopic characteristics makes these materials ideal candidates for mid-IR tunable laser systems This article reviews transition metal doped II–VI materials and recent progress in Cr- and Fe-doped solid-state mid-IR lasers
207 citations
Book•
19 Nov 2010
TL;DR: Theoretical modeling of Neodymium Random Lasers: External seeding, design, and second harmonic generation as mentioned in this paper, as well as the application of random Lasers in a variety of applications.
Abstract: Lasers with Nonresonant Feedback and Laserlike Emission from Powders: Early Ideas and Experiments- Neodymium Random Lasers: Experimental Studies of Stimulated Emission- Propagation of Light in Neodymium Random Lasers- Theoretical Modeling of Neodymium Random Lasers- Engineering Aspects of Neodymium Random Lasers: External Seeding, Design, and Second Harmonic Generation- Random Lasers Pumped with Electron Beam- Semiconductor Random Lasers- Dye and Polymer Random Lasers- Other Types of Solid-State Random Lasers- Applications of Random Lasers
189 citations
TL;DR: In this article, the authors used a precision-calibrated photodiode as the fundamental metrology reference to determine the relative throughput of the PanSTARRS telescope and the Gigapixel imager, from 400 nm to 1050 nm.
Abstract: We have used a precision-calibrated photodiode as the fundamental metrology reference in order to determine the relative throughput of the PanSTARRS telescope and the Gigapixel imager, from 400 nm to 1050 nm. Our technique uses a tunable laser as a source of illumination on a transmissive flat-field screen. We determine the full-aperture system throughput as a function of wavelength, including (in a single integral measurement) the mirror reflectivity, the transmission functions of the filters and the corrector optics, and the detector quantum efficiency, by comparing the light seen by each pixel in the CCD array to that measured by a precision-calibrated silicon photodiode. This method allows us to determine the relative throughput of the entire system as a function of wavelength, for each pixel in the instrument, without observations of celestial standards. We present promising initial results from this characterization of the PanSTARRS system, and we use synthetic photometry to assess the photometric perturbations due to throughput variation across the field of view.
162 citations
TL;DR: Fiber lasers are entering the realm of kilowatt powers in continuous as well as in pulse operation with diffraction-limited beam quality, and this power evolution is reviewed.
Abstract: The first rare-earth-doped fiber lasers were operated in the early sixties and produced a few milliwatts at a wavelength around 1 μm. For the next several decades, fiber lasers were little more than a low-power laboratory curiosity. Recently, however, fiber lasers are entering the realm of kilowatt powers in continuous as well as in pulse operation with diffraction-limited beam quality. In this article we review this power evolution.
162 citations
TL;DR: In this article, the continuous wave laser action on GaN-based vertical cavity surface emitting laser at room temperature was demonstrated. But the laser structure consists of a ten-pair Ta2O5/SiO2 distributed Bragg reflector (DBR), a 7λ-thick optical cavity, ten-pairs InGaN/GaN multiquantum wells with an AlGaN electron blocking layer, and a 29-pair AlN/ GaN DBR.
Abstract: We report the demonstration of the continuous wave laser action on GaN-based vertical cavity surface emitting lasers at room temperature. The laser structure consists of a ten-pair Ta2O5/SiO2 distributed Bragg reflector (DBR), a 7λ-thick optical cavity, ten-pairs InGaN/GaN multiquantum wells with an AlGaN electron blocking layer, and a 29-pair AlN/GaN DBR. The laser has a threshold current of about 9.7 mA corresponding to the current density of about 12.4 kA/cm2 and a turn-on voltage about 4.3 V at 300 K. The lasing wavelength was 412 nm with a linewidth of about 0.5 nm. A spontaneous emission coupling efficiency factor of about 5×10−3 and the degree of polarization of about 55% were measured, respectively. The laser beam has a narrow divergence angle of about 8°.
143 citations
TL;DR: The power scaling concept of the MIXSEL is demonstrated using optimized quantum dot saturable absorbers in an antiresonant structure design combined with an improved thermal management by wafer removal and mounting of the 8-µm thick MixSEL structure directly onto a CVD-diamond heat spreader.
Abstract: High-power ultrafast lasers are important for numerous industrial and scientific applications. Current multi-watt systems, however, are based on relatively complex laser concepts, for example using additional intracavity elements for pulse formation. Moving towards a higher level of integration would reduce complexity, packaging, and manufacturing cost, which are important requirements for mass production. Semiconductor lasers are well established for such applications, and optically-pumped vertical external cavity surface emitting lasers (VECSELs) are most promising for higher power applications, generating the highest power in fundamental transverse mode (>20 W) to date. Ultrashort pulses have been demonstrated using passive modelocking with a semiconductor saturable absorber mirror (SESAM), achieving for example 2.1-W average power, sub-100-fs pulse duration, and 50-GHz pulse repetition rate. Previously the integration of both the gain and absorber elements into a single wafer was demonstrated with the MIXSEL (modelocked integrated external-cavity surface emitting laser) but with limited average output power (<200 mW). We have demonstrated the power scaling concept of the MIXSEL using optimized quantum dot saturable absorbers in an antiresonant structure design combined with an improved thermal management by wafer removal and mounting of the 8-µm thick MIXSEL structure directly onto a CVD-diamond heat spreader. The simple straight cavity with only two components has generated 28-ps pulses at 2.5-GHz repetition rate and an average output power of 6.4 W, which is higher than for any other modelocked semiconductor laser.
TL;DR: In this paper, a substrate-free metal-cavity surface-emitting microlaser with both top and sidewall metal and a bottom distributed Bragg reflector as the cavity structure is presented.
Abstract: We propose and realize a substrate-free metal-cavity surface-emitting microlaser with both top and sidewall metal and a bottom distributed Bragg reflector as the cavity structure. The transfer-matrix method is used to design the laser structure based on the round-trip resonance condition inside the cavity. The laser is 2.0 μm in diameter and 2.5 μm in height, and operates at room temperature with continuous-wave mode. Flip-bonding the device to a silicon substrate with a conductive metal provides efficient heat removal. A high characteristic temperature about 425 K is observed from 10 to 27 °C.
TL;DR: High power (2.1W) low noise single frequency operation of a tunable compact verical-external-cavity surface-emitting- laser exhibiting a high beam quality and key parameters limiting the laser power and coherence are studied.
Abstract: We demonstrate high power (2.1 W) low noise single frequency operation of a tunable compact verical–external–cavity surface–emitting–laser exhibiting a high beam quality. We took advantage of thermal lens–based stability to develop a short (3 – 10 mm) plano–plano external cavity without any intracavity filter. The semiconductor structure emitting at 1µm is optically pumped by a 8W commercial 808 nm multimode diode laser at large incidence angle. For heat management purpose the GaAs-based VECSEL membrane was bonded on a SiC substrate. We measured a low divergence quasi-circular TEM00 beam (M2 = 1.2) close to diffraction limit, with a linear light polarization (> 30 dB).We simulated the steady state laser beam of this unstable cavity using Fresnel diffraction. The side mode suppression ratio is > 45 dB. The free running laser linewidth is 37 kHz limited by pump induced thermal fluctuations. Thanks to this high-Q external cavity approach, the frequency noise is low and the dynamics is in the relaxation-oscillation-free regime, exhibiting low intensity noise (< 0.1%), with a cutoff frequency ~ 41MHz above which the shot noise level is reached. The key parameters limiting the laser power and coherence are studied. This design/properties can be extended to other wavelengths.
TL;DR: In this paper, the authors demonstrate a compact wavelength tunable laser module using hybrid integrated semiconductor optical amplifier and silicon waveguide resonators, which can achieve +8 dBm fiber coupled power under the module temperature of 70°C.
Abstract: Silicon photonics is expected to reduce size and cost of photonic devices and realize large scale photonic integrated circuits for telecom and datacom applications. In this paper, we demonstrate a compact wavelength tunable laser module using hybrid integrated semiconductor optical amplifier and silicon waveguide resonators. The power consumption of the laser module is 1 W to obtain +8 dBm fiber coupled power under the module temperature of 70°C. Such integration technology broadens design flexibility of silicon-based photonic devices and their applications.
TL;DR: Two different laser configurations for high-power tunable thulium fiber lasers are reported on: one is a single oscillator utilizing a volume Bragg grating for wavelength stabilization; the other is a master oscillator power amplifier system with the oscillator stabilized and made tunable by a diffraction grating.
Abstract: Applications requiring long-range atmospheric propagation are driving the development of high-power thulium fiber lasers. We report on the performance of two different laser configurations for high-power tunable thulium fiber lasers: one is a single oscillator utilizing a volume Bragg grating for wavelength stabilization; the other is a master oscillator power amplifier system with the oscillator stabilized and made tunable by a diffraction grating. Each configuration provides >150W of average power, >50% slope efficiency, narrow output linewidth, and >100nm tunability in the wavelength range around 2μm.
TL;DR: In this article, the authors discuss fundamental aspects on the spectroscopy and laser dynamics of dual-wavelength laser systems and make general conclusions regarding the successful operation of multiwidth laser systems.
Abstract: Dual wavelength lasers are discussed, covering fundamental aspects on the spectroscopy and laser dynamics of these systems. Results on Tm:Ho:Er:YAG dual wavelength laser action (Ho at 2.1 μm and Er at 2.9 μm) as well as Nd:YAG (1.06 and 1.3 μm) are presented as examples of such dual wavelength systems. Dual wavelength lasers are not common, but there are criteria that govern their behavior. Based on experimental studies demonstrating simultaneous dual wavelength lasing, some general conclusions regarding the successful operation of multi-wavelength lasers can be made.
TL;DR: A 1542-nm planar-waveguide external cavity laser (PW-ECL) is shown to have a sufficiently low level of noise to be suitable for precision measurement applications and to have the advantage of the compactness of a standard butterfly package, low cost, and a simple design.
Abstract: A 1542-nm planar-waveguide external cavity laser (PW-ECL) is shown to have a sufficiently low level of frequency and intensity noise to be suitable for precision measurement applications. The frequency noise and intensity noise of the PW-ECL was comparable or better than the nonplanar ring oscillator (NPRO) and fiber laser between 0.1 mHz to 100 kHz. Controllability of the PW-ECL was demonstrated by stabilizing its frequency to acetylene (13C2H2) at 10(exp -13) level of Allan deviation. The PW-ECL also has the advantage of the compactness of a standard butterfly package, low cost, and a simple design consisting of a semiconductor gain media coupled to a planar-waveguide Bragg reflector. These features would make the PW-ECL suitable for precision measurements, including compact optical frequency standards, space lidar, and space interferometry
TL;DR: In this article, the Bridgman-technique-grown active crystals Cr2+:ZnMgSe and Fe2+):ZnSe were investigated at room temperature from the point of view of laser parameters.
Abstract: The laser properties of Bridgman method grown active crystals Cr2+:ZnMgSe and Fe2+:ZnSe were investigated at room temperature from the point of view of laser parameters. Cr2+:ZnMgSe crystal was pumped by the 1.66 μm wavelength radiation of pulsed Er3+:YAP laser. The maximum reached energy and slope efficiency with respect to absorbed pump energy was 4 mJ and 15%, respectively. The Cr2+:ZnMgSe laser oscillation spectrum was about 90 nm wide and centered at 2.47 μm. With the CaF2 prism placed inside the laser resonator the tuning within 2.3 – 2.6 μm range was demonstrated. The pumping of Fe2+:ZnSe crystal was made by Q-switched Er:YAG laser radiation with the wavelength 2.94 μm. The measured maximum output Fe2+:ZnSe laser energy was 0.58 mJ with the generated wavelengths 4.3 – 4.6 μm and with a slope efficiency in respect to absorbed energy of 38%. The study demonstrates quite promising perspectives of the Bridgman-technique-grown Cr2+:ZnMgSe and Fe2+:ZnSe crystals for development of the efficient at room-temperature working mid-IR tunable laser sources.
TL;DR: In this article, a Quantum Cascade Tunable Infrared Laser Differential Absorption Spectrometer (QC-TILDAS) for measurements of ammonia (NH3) has been evaluated under both laboratory and field conditions.
Abstract: . A compact, fast-response Quantum Cascade Tunable Infrared Laser Differential Absorption Spectrometer (QC-TILDAS) for measurements of ammonia (NH3) has been evaluated under both laboratory and field conditions. Absorption of radiation from a pulsed, thermoelectrically cooled QC laser occurs at reduced pressure in a 0.5 L multiple pass absorption cell with an effective path length of 76 m. Detection is achieved using a thermoelectrically-cooled Mercury Cadmium Telluride (HgCdTe) infrared detector. A novel sampling inlet was used, consisting of a short, heated, quartz tube with a hydrophobic coating to minimize the adsorption of NH3 to surfaces. The inlet contains a critical orifice that reduces the pressure, a virtual impactor for separation of particles, and additional ports for delivering NH3-free background air and calibration gas standards. The level of noise in this instrument has been found to be 0.23 ppb at 1 Hz. The sampling technique has been compared to the results of a conventional lead salt Tunable Diode Laser Absorption Spectrometer (TDLAS) during a laboratory intercomparison. The effect of humidity and heat on the surface interaction of NH3 with sample tubing was investigated at mixing ratios ranging from 30–1000 ppb. Humidity was seen to worsen the NH3 time response and considerable improvement was observed when using a heated sampling line. A field intercomparison of the QC-TILDAS with a modified Thermo 42CTL chemiluminescence-based analyzer was also performed at Environment Canada's Centre for Atmospheric Research Experiments (CARE) in the rural town of Egbert, ON between May–July 2008. Background tests and calibrations using two different permeation tube sources and an NH3 gas cylinder were regularly carried out throughout the study. Results indicate a very good correlation at 1 min time resolution (R2 = 0.93) between the two instruments at the beginning of the study, when regular background subtraction was applied to the QC-TILDAS. An overall good correlation of R2 = 0.85 was obtained over the entire two month data set, where the majority of the spread can be attributed to differences in inlet design and background subtraction methods.
TL;DR: A widely tunable dual-wavelength Erbium-doped fiber laser that uses two micro-heater-integrated Fabry-Perot laser diodes and two fiber Bragg gratings for tunable continuous-wave (CW) terahertz (THz) radiation is proposed.
Abstract: We propose a widely tunable dual-wavelength Erbium-doped fiber laser that uses two micro-heater-integrated Fabry-Perot laser diodes (FP-LDs) and two fiber Bragg gratings (FBGs) for tunable continuous-wave (CW) terahertz (THz) radiation. Each wavelength can be independently tuned by using an FP-LD and an FBG. The wavelength fine tuning is achieved by simultaneously applying current to the micro-heater on the FP-LD and strain to the FBG. The side-mode suppression ratio is more than 35 dB for both wavelengths. The wavelength spacing of the dual wavelength can be continuously tuned from 3.2 nm to 9.6 nm. Continuous frequency tuning of the CW THz radiation is also successfully achieved using an InGaAs-based photomixer with our dual-wavelength fiber laser as the optical beat source. The emitted CW THz radiation is continuously tuned from 0.3 to 0.8 THz.
TL;DR: In this paper, a low-threshold organic laser device based on semiconducting poly(9,9′-dioctylfluoren-2,7-diyl-alt-benzothiadiazole) (F8BT) encapsulated in a mechanically stretchable polydimethylsiloxane (PDMS) matrix is presented.
Abstract: Herein we report a low-threshold organic laser device based on semiconducting poly(9,9′-dioctylfluoren-2,7-diyl-alt-benzothiadiazole) (F8BT) encapsulated in a mechanically stretchable polydimethylsiloxane (PDMS) matrix. We take advantage of the natural flexibility of PDMS to alter the periodicity of the distributed feedback grating which in turn tunes the gain wavelength at which the resonant feedback is obtained. This way, we demonstrate that low-threshold lasing [6.1 μJ cm−2 (5.3 nJ)] is maintained over a large stretching range of 0%–7% which translates into a tuning range of about 20 nm.
TL;DR: A record broadly tunable high-power external cavity InAs/GaAs quantum-dot diode laser with a tuning range of 202 nm (1122 nm-1324 nm) is demonstrated.
Abstract: A record broadly tunable high-power external cavity InAs/GaAs quantum-dot diode laser with a tuning range of 202 nm (1122 nm-1324 nm) is demonstrated. A maximum output power of 480 mW and a side-mode suppression ratio greater than 45 dB are achieved in the central part of the tuning range. We exploit a number of strategies for enhancing the tuning range of external cavity quantum-dot lasers. Different waveguide designs, laser configurations and operation conditions (pump current and temperature) are investigated for optimization of output power and tunability.
TL;DR: Edge emitting, terahertz quantum cascade photonic-wire lasers, based on a third order Bragg grating are presented, showing more than 10mW output power and more than 200mW/A slope efficiency at 10K continuous-wave operation.
Abstract: Edge emitting, terahertz quantum cascade photonic-wire lasers, based on a third order Bragg grating are presented. Devices with a power consumption as low as 300mW, with a single frequency output power of more than 1.5mW are demonstrated. Their maximum operating temperature in continuous-wave mode operation is 110K and the emission is concentrated in a narrow beam (~30° divergence). Larger structure based on the same design show more than 10mW output power and more than 200mW/A slope efficiency at 10K continuous-wave operation.
TL;DR: In this paper, a near-infrared tunable diode laser spectrometer called TDLAS has been developed that combines telecommunication-type as well as new-generation antimonide laser diodes to measure C2H2, H2O, CO2 and their isotopologues in the near infrared.
Abstract: A near-infrared tunable diode laser spectrometer called TDLAS has been developed that combines telecommunication-type as well as new-generation antimonide laser diodes to measure C2H2, H2O, CO2 and their isotopologues in the near infrared. This sensor is devoted to the in situ analysis of the soil of the Martian satellite PHOBOS, within the framework of the Russian space mission PHOBOS-GRUNT. In the first part of the paper, we report accurate spectroscopic measurements of C2H2 and 13C12CH2 near 1.533 μm, of H2O and CO2 at 2.682 μm and of the isotopologues 13C16O2 and 16O12C18O near 2.041 μm and H2
17O, H2
18O and HDO near 2.642 μm. The achieved line strengths are thoroughly compared to data from molecular databases or from former experimental determinations. In the second part of the paper, we describe the TDLAS spectrometer for the PHOBOS-GRUNT mission.
TL;DR: It is reported for the first time (to the authors' knowledge) a diode-pumped Nd:YAG laser emitting at 869 nm based on the (4)F(3/2)-(4)I(9/2) transition, generally used for a 946 nm emission.
Abstract: We report for the first time (to our knowledge) a diode-pumped Nd:YAG laser emitting at 869nm based on the F3/24-I9/24 transition, generally used for a 946nm emission. Power of 453mW at 869nm has been achieved in cw operation with a fiber-coupled laser diode emitting 35.4W at 809nm. Intracavity second-harmonic generation in the cw mode has also been demonstrated with power of 118mW at 435nm by using a BiB3O6 nonlinear crystal. In our experiment, we used a LiNbO3 crystal lens to complement the thermal lens of the laser rod, and we obtained good beam quality and high output power stability.
TL;DR: Three all-fiber Ho-doped lasers emitting in the range of 2050-2100 nm were fabricated and the output power was found to be as high as 10 W, the efficiency slope being 30%.
Abstract: Three all-fiber Ho-doped lasers emitting in the range of 2050-2100 nm were fabricated. The lasers were pumped by an Yb-doped fiber laser at 1147 nm with a power up to 35 W. For all the lasers tested, the output power was found to be as high as 10 W, the efficiency slope being 30%.
TL;DR: New BODIPY dyes with two 4-formylphenyl, 4-2-dimethoxycarbonylvinyl and 4-(2,2-dicyanovinyl)phenyl groups at the 3- and 5-positions have been successfully designed and synthesized via palladium-catalyzed coupling reaction or Knoevenagel-type condensations.
Abstract: New BODIPY dyes with two 4-formylphenyl, 4-(2,2-dimethoxycarbonylvinyl)phenyl and 4-(2,2-dicyanovinyl)phenyl groups at the 3- and 5-positions have been successfully designed and synthesized via palladium-catalyzed coupling reaction or Knoevenagel-type condensations. Structural modification of the BODIPY core via conjugation-extending residues significantly affects the spectroscopy and photophysical properties of the BODIPY fluorophore. These substituents cause the largest bathochromic shift in both absorption and emission spectra, which are shifted toward the red compared to its 4-phenylsubstituted analogue. Additionally, the fluorescence quantum yields and the Stokes shifts are also significantly higher than the corresponding phenyl-substituted dye. New BODIPY dyes have a high laser photostability, superior to that of commercial dyes with laser emission in the same spectral region, such as Perylene Red and Rhodamine 640. The substitution introduced in these derivatives allows to obtain tunable laser emission with a bandwidth of 0.15 cm−1 and a tuning range of up to 50 nm. So with these three dyes it is possible to cover the spectral range 590–680 nm in a continuous way and with stable laser emission and small linewidth.
TL;DR: This work demonstrated a 380 fs dual-wavelength independently mode-locked Yb∶YAG ceramic laser at 1033.6 and 1047.6 nm, which is the first dual-Wavelength mode locking achieved in Yb-doped solid-state lasers.
Abstract: We experimentally demonstrated a dual-wavelength independently mode-locked Yb:YAG ceramic laser in a single cavity. Dual-wavelength mode locking at 1033.6 and 1047.6 nm was operated simultaneously in one beam. Each pulse width was measured to be approximately 380 fs using an autocorrelator. The spectral widths were 4.50 nm centered at 1033.6 nm and 3.08 nm centered at 1047.6 nm. To the best of our knowledge, this is the first dual-wavelength mode locking achieved in Yb-doped solid-state lasers.
TL;DR: A tunable erbium doped fiber laser based on a Fabry-Perot (F-P) cavity tuned by an electrostatic actuator was proposed in this article. But the performance of the F-P cavity was not evaluated.
Abstract: We propose a tunable erbium doped fiber laser based on a Fabry-Perot (F-P) cavity tuned by an electrostatic actuator. The device is made of single crystalline silicon. The F-P cavity consists of two Bragg mirrors, one being displaced by a comb-drives actuator. The F-P cavity, grooves for optical fibers and electro-mechanical structure are fabricated by deep reactive ion etching on a 70 μm silicon on insulator wafer and are integrated in a ring fiber laser. The resulting tunable fiber laser has a tuning range of 35 nm in the C-band and a spectral width of less than 0.06 nm. The maximum applied voltage for full tuning of the laser is 37 V. The mechanical resonance frequency of the actuated mirror is 14.4 kHz allowing fast tuning of the laser. The maximum output power is 1.8 mW.
TL;DR: Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers (OF-CERPAS), a "zero-background" method which increases selectivity and sensitivity, and its sensitivity scales with laser power.
Abstract: Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers (OF-CERPAS) is introduced as a novel technique for ultratrace gas analysis and high-resolution spectroscopy. In the scheme, a single-mode cw diode laser (3 mW, 635 nm) is coupled into a high-finesse linear cavity and stabilized to the cavity by optical feedback. Inside the cavity, a build-up of laser power to at least 2.5 W occurs. Absorbing gas phase species inside the cavity are detected with high sensitivity by the photoacoustic effect using a microphone embedded in the cavity. To increase sensitivity further, coupling into the cavity is modulated at a frequency corresponding to a longitudinal resonance of an organ pipe acoustic resonator (f=1.35 kHz and Q approximately 10). The technique has been characterized by measuring very weak water overtone transitions near 635 nm. Normalized noise-equivalent absorption coefficients are determined as alpha approximately 4.4x10(-9) cm(-1) s(1/2) (1 s integration time) and 2.6x10(-11) cm(-1) s(1/2) W (1 s integration time and 1 W laser power). These sensitivities compare favorably with existing state-of-the-art techniques. As an advantage, OF-CERPAS is a "zero-background" method which increases selectivity and sensitivity, and its sensitivity scales with laser power.