Showing papers on "Fiber laser published in 1994"
TL;DR: Passively Q-switched 1.064-microm microchip lasers have been constructed from thin pieces of Nd(3+):YAG bonded to thin pieces with peak power in excess of 180 MW/cm(2) in a single-frequency TEM(00) mode.
Abstract: Passively Q-switched 1.064-microm microchip lasers have been constructed from thin pieces of Nd(3+):YAG bonded to thin pieces of Cr(4+):YAG. When pumped with the unfocused 1.2-W output of a fiber-coupled diode, these devices produced 11-microJ pulses of 337-ps duration at a pulse repetition rate of 6 kHz in a single-frequency TEM(00) mode. The peak power of the lasers was in excess of 180 MW/cm(2).
439 citations
Patent•
27 Oct 1994
TL;DR: In this paper, the optical fiber gain medium has two or more non-concentric core regions, each of which is capable of gain or lasing when optically pumped when the fiber medium is single clad or double clad, with multiple core regions embedded within a common cladding region or within separate cladding regions.
Abstract: A fiber laser or amplifier in which the optical fiber gain medium has two or more nonconcentric core regions, each of which is capable of gain or lasing when optically pumped. The fiber may be single clad or double clad, with multiple core regions embedded within a common cladding region or within separate cladding regions. The core regions may be arranged in a linear, closely spaced hexagonal, rectangular matrix or some other configuration and positioned symmetrically or noncentrosymmetrically, centered or off-center within the core region or regions. The spacing between neighboring core regions may be far enough apart to minimize optical interaction between cores for independent light amplifying or laser action or be close enough for phase-locked operation of the multiple cores to occur. The cores may be doped with the same or different active ionic species, of which one or more could be upconverting ions. If several dopants are present, the multiple pump wavelengths could be provided simultaneously or one could be selected for simultaneous multiple wavelength amplification or lasing or selected single wavelength amplification or lasing. The multi-core output can be imaged by a lens or collimated by a lens array then focused to a spot.
262 citations
TL;DR: A self-starting additive-pulse model-ocked (APM) all-fiber ring cavity laser operating in the negative group velocity regime is analyzed in this paper, where the advantages of using a ring cavity with an isolator are discussed.
Abstract: A self-starting additive-pulse modelocked (APM) all-fiber ring cavity laser operating in the negative group velocity regime is analyzed. The advantages of using a ring cavity with an isolator are discussed. The "figure eight" and the Sagnac loop reflector fiber laser are investigated in a novel way, and one form of their operation is related to the master equation of APM. We point out that the ring laser has an advantage with respect to self-starting. >
252 citations
TL;DR: In this article, a thorough experimental investigation of the phenomenon of soliton resonance sideband generation in femtosecond fiber lasers is presented, and the dependence of the sideband wavelengths on the dispersion and pulse length is confirmed.
Abstract: We present a thorough experimental investigation of the phenomenon of soliton resonance sideband generation in femtosecond fiber lasers. The dependence of the sideband wavelengths on the dispersion and pulse length is confirmed. Third order dispersion is found to play a significant role in determining the sideband spectrum. We show that the minimum pulse length obtained in a fiber laser is determined by the cavity dispersion and relate this to loss into the sidebands. We show how the sideband spectrum can be used as a diagnostic of the fiber parameters and of the formation of ultrashort pulses in the laser. >
251 citations
TL;DR: In this paper, a harmonically and regeneratively modelocked erbium fiber ring laser at 1.55 mu m for the first time was reported. But this was achieved with a high speed photodetector and a high Q dielectric filter.
Abstract: The authors report the operation of a harmonically and regeneratively modelocked erbium fibre ring laser at 1.55 mu m for the first time. Harmonic regenerative modelocking was achieved by feeding back the harmonic longitudinal beat signal which was detected with a high speed photodetector and a high Q dielectric filter. The repetition rate was 10 GHz and the soliton effect shortened-the pulse width from 7.0 to 2.7 ps.
249 citations
TL;DR: This work reports what is to their knowledge the first fiber distributed-feedback laser using a single Bragg grating at 1.5 microm written directly into a 2-cm-long Er(3+)-doped fiber codoped with Yb( 3+).
Abstract: We report what is to our knowledge the first fiber distributed-feedback laser using a single Bragg grating at 1.5 microm written directly into a 2-cm-long Er(3+)-doped fiber codoped with Yb(3+). We obtained robust single-frequency operation by either using one end reflector or locally heating the center of the grating to create the necessary phase shift.
246 citations
TL;DR: In this article, an analytical model for two-, three-, and four-level system rare-earth-doped fiber amplifiers and lasers is presented, where fiber-amplifier gain is expressed in terms of attenuation coefficients, intrinsic saturation powers, and cross-saturation powers at the pump and signal wavelengths.
Abstract: An analytical model for two-, three-, and four-level system rare-earth-doped fiber amplifiers and lasers is presented. The theory is applicable to dopants such as erbium, neodymium, thulium; praseodymium, and ytterbium. Fiber-amplifier gain is expressed in terms of attenuation coefficients, intrinsic saturation powers, and cross-saturation powers at the pump and signal wavelengths. These parameters can be directly determined from one- and two-beam fiber-transmission measurements. System-independent formulas are given for the slopes and thresholds of ring and linear fiber lasers. Good agreement between theory and experiment has been shown for erbium-doped fiber amplifiers and lasers and thulium-doped fiber lasers. Because of the finite-pump-level lifetime, three- and four-level models predict a flattening of the fiber laser slope at higher pumping powers when the fiber is shorter than the optimum length. Approximate system-independent solutions are also given for fiber amplifiers with excited-state absorption at either the pump or signal wavelengths. A novel technique, requiring only one tunable light source, is proposed for finding the best pump wavelength when pump ESA is present. The two-level analytical model recently developed for erbium-doped fibers is a special case of this theory. >
206 citations
TL;DR: In this paper, the authors show that by reducing the system nonlinearity via pulse stretching and employing net positive dispersion cavities, pulses of sub-100fs duration and ≳100 pJ energy are readily generated.
Abstract: To date most passively mode‐locked erbium‐doped fiber laser systems have employed solitons for short pulse generation, and ultrashort high energy pulses have been difficult to achieve. We show that by reducing the system nonlinearity via pulse stretching and employing net positive dispersion cavities, pulses of sub‐100‐fs duration and ≳100 pJ energy are readily generated. Data are presented for varying net dispersion in a fiber ring.
184 citations
TL;DR: A cavity-dumped self-mode-locked Ti:sapphire laser operating on a 10-fs time scale produces a white-light continuum that shows great potential for compression on injection of the output of this laser into a fiber.
Abstract: We report on a cavity-dumped self-mode-locked Ti:sapphire laser operating on a 10-fs time scale. Pulses with energies exceeding 60 nJ and peak powers of 5 MW were generated at repetition rates as high as 200 kHz. On injection of the output of this laser into a fiber, a white-light continuum is produced that shows great potential for compression.
154 citations
TL;DR: The power levels suggest that erbium-doped fiber lasers may replace bulk solid-state lasers, such as the color-center laser, for some applications.
Abstract: We report a self-starting stretched-pulse polarization additive-pulse mode-locked erbium-doped fiber ring laser with high output power. By using the light normally absorbed by the intracavity polarizer as the output, we obtained pulses with energies greater than 0.5 nJ at a repetition rate of 48 MHz. External chirp compensation was used to shorten the highly chirped output pulses to durations of less than 100 fs. The power levels suggest that erbium-doped fiber lasers may replace bulk solid-state lasers, such as the color-center laser, for some applications.
154 citations
TL;DR: Wavelength modulation with second-harmonic detection, applied simultaneously in the O2 measurements, yielded a minimum detectable absorbance and an O2 detectivity of 6.3 parts in 106 in a 1-m path length.
Abstract: A multiplexed diode-laser sensor system has been developed to monitor multiple species and measure multiple flowfield parameters along a single path with optical fibers and scanned-laser absorption techniques. Two InGaAsP lasers were tuned over H2O transitions near 1347 and 1392 nm, and an AlGaAs laser was tuned over an O2 transition near 760.65 nm to record fully resolved absorption concurrently at a repetition rate of 2 kHz. The system was applied to measure H2O, O2, and temperature simultaneously in a heated static cell and in room air. Wavelength modulation with second-harmonic detection, applied simultaneously in the O2 measurements, yielded a minimum detectable absorbance of 1.6 × 10−6/Hz1/2 and an O2 detectivity of 6.3 parts in 106 in a 1-m path length.
TL;DR: A new method for introducing a chirp on a fiber Bragg grating through the use of a controllable temperature gradient device, which allows the linear chirP conditions to be totally adjustable in a nondestructive repeatable manner.
Abstract: We propose a new method for introducing a chirp on a fiber Bragg grating. Uniformly written fiber Bragg gratings are linearly chirped through the use of a controllable temperature gradient device. This device allows the linear chirp conditions to be totally adjustable in a nondestructive repeatable manner. These conditions can be selected with great precision and are very stable, once defined. To characterize the resulting chirped gratings, we have measured their dispersion. Dispersion of the order of 200 ps/nm have been obtained for 1-cm-long fiber Bragg gratings with temperature gradients near 20 degrees C.
Patent•
26 Jan 1994
TL;DR: In this article, a multiuser remote active multipoint fiber laser sensor includes a plurality of fiber lasers (12, 14, 16), each having a pair of Bragg gratings (18, 20), embedded in a fiber and excited by a common pump light.
Abstract: A remote active multipoint fiber laser sensor includes a plurality of fiber lasers (12, 14, 16), each having a pair of Bragg gratings (18, 20), embedded in a fiber (10) and excited by a common pump light (30). The lasers (12, 14, 16) lase at different longitudinal modes (lasing wavelengths) and emit light (32, 34, 36), at their respective wavelengths (μ1, μ2, μn). The lasing wavelength of each laser shifts due to perturbations, such as strain or temperature, applied thereto. The output light (32, 34, 36) is fed to a spectrum analyzer (50) where the wavelength shift is analyzed. A signal processor (54) reads the wavelength shift and provides a signal on lines (56) indicative of the perturbation at each of the lasers/sensors (12-16). Alternatively, a single laser may be used as a single sensor. Alternatively, birefringent fiber may be used as the fiber cavities (21) and the two polarizations are beat together to form a lower difference or ''beat'' frequency, thereby allowing lower frequency detection devices to be used.
TL;DR: In this article, compressive stress has been used to continuously tune a single-frequency Bragg grating fiber laser over 32 nm without mode hopping and a master-oscillator/power-amplifier configuration and active noise reduction were implemented to maintain a constant, low-noise, 3mW lasing power over the tuning range.
Abstract: Compressive stress has been used to continuously wavelength tune a single-frequency Bragg grating fiber laser over 32 nm without mode hopping. A master-oscillator/power-amplifier configuration and active noise reduction were implemented to maintain a constant, low-noise, 3-mW lasing power over the tuning range.
Patent•
21 Oct 1994
TL;DR: In this article, the Kerr model-knocking was applied to an erbium fiber laser, where a chirped fiber Bragg grating was employed as the dispersive element.
Abstract: The invention relates to modelocked lasers including highly dispersive optical elements. The dispersive optical elements increase the oscillation pulse width inside the laser oscillators, which reduces the nonlinearity of the laser cavity for a given oscillating pulse energy. Compared to conventionally designed modelocked lasers, an increase in output pulse energy by one to three orders is achieved. As way of example, the technique is applied to an erbium fiber laser, where a chirped fiber Bragg grating is employed as the dispersive element. By using a Kerr-modelocking technique, a high nonlinearity may be sustained inside the fiber laser cavity, which leads to the generation of pulses with psec widths and energies up to 2 nJ. The large bandwidth of the chirped fiber Bragg grating allows a wavelength tuning range in excess of 10 nm, which is achieved by polarization control and a control of the gain spectrum of the laser.
TL;DR: An environmentally stable Kerr-type mode-locked erbium fiber laser producing 360-fs near-bandwidth-limited pulses is demonstrated.
Abstract: We demonstrate an environmentally stable Kerr-type mode-locked erbium fiber laser producing 360-fs near-bandwidth-limited pulses. Environmentally stable operation is possible in the presence of nonpolarization-maintaining fiber components provided that their overall length is short compared with the length of the polarization-maintaining fiber components. The pulses are generated at a stable repetition rate of 27 MHz and have an energy content of 60 pJ.
TL;DR: A multiwavelength comb is obtained from Er(3+) - and Nd(3+)-doped fiber lasers by incorporation of a section of multimode optical fiber into an otherwise single-mode fiber ring cavity.
Abstract: A multiwavelength comb is obtained from Er(3+) - and Nd(3+)-doped fiber lasers by incorporation of a section of multimode optical fiber into an otherwise single-mode fiber ring cavity. This combination of fiber types acts as a wavelength-dependent filter in the laser through spatial mode beating between the LP(01) and LP(11) modes in the multimode fiber.
TL;DR: In this article, the authors measured the finesse of a high Q resonator and used it for the first time with a stable Er/sup +3/ fiber grating laser source which was thermally tuned.
Abstract: Phosphorus doped silica on silicon waveguide propagation loss, bend loss and their polarization dependence have been measured using a set of different radii ring resonators. For a 30 mm ring radius a finesse of 132 was measured and the inferred propagation loss was 0.85 dB/m, the lowest value yet reported. To characterize the finesse of the high Q resonator we proposed and used for the first time a stable Er/sup +3/ fiber grating laser source which was thermally tuned. This configuration provides improved and accurate measurements capability for finesse values in the range well beyond 100. >
TL;DR: In this paper, the chirp-compensated supercontinuum generated by 2.5 ps Er3+-doped fiber laser pulses with time-bandwidth products of 0.11 -0.14 are generated at 6.3 GHz.
Abstract: 0.25 – 0.67 ps optical pulses with time-bandwidth products of 0.11 – 0.14 are generated at 6.3 GHz over 1530 – 1562 nm by spectrally filtering the chirp-compensated supercontinuum generated by 2.5 ps Er3+-doped fibre laser pulses. The proposed scheme features a multiwavelength GHz output over a continuous wavelength range, and offers a wide variety of applications in ultrafast all-optical TDM/WDM networks.
TL;DR: A novel optical fiber that consists of a chain of alternating segments of standard telecommunication fiber and dispersion-shifted fiber is proposed for the generation of a soliton pulse train based on nonlinear transformation of an optical beat signal.
Abstract: A novel optical fiber [comblike dispersion-profiled fiber (CDPF)] that consists of a chain of alternating segments of standard telecommunication fiber and dispersion-shifted fiber is proposed for the generation of a soliton pulse train based on nonlinear transformation of an optical beat signal. A totally integrated all-optical fiber source of a 59.1-GHz train of 2.2-ps solitons is demonstrated with a CDPF. For a beat signal generator we use a dual-frequency erbium fiber laser incorporating fiber grating reflectors that provides 16-kHz linewidths and a low phase noise of optical beating (<5 × 10−5). Significant suppression of stimulated Brillouin scattering, which is essential for this technique, is achieved in the CDPF.
TL;DR: In this paper, the authors used a calibrated, narrow-linewidth, single-frequency, continuously wavelength-tunable erbium fiber laser to the interrogation of a multipoint Bragg temperature sensor.
Abstract: This paper reports on the application of a calibrated, narrow-linewidth, single-frequency, continuously wavelength-tunable erbium fiber laser to the interrogation of a multipoint Bragg grating temperature sensor. The fiber laser was wavelength-tuned, through an array of three fiber Bragg grating sensors, to determine the temperature of each individual grating. The temperatures of the three gratings were measured as a function of grating Bragg wavelength. The minimum wavelength resolution, due to electro-mechanical repeatability, of the fiber laser source/analyzer was determined to be approximately 2.3 picometers. This corresponds to a frequency resolution of approximately 300 MHz. >
TL;DR: In this paper, a numerical model based on the split step Fourier method suggests that this pulse mode of operation may be attributed to the Kerr-type nonlinearity of the optical fiber.
Abstract: Lasers with frequency shifted feedback may spontaneously generate periodic trains of short optical pulses. Frequency shifts as small as several kilohertz per roundtrip are shown to sustain pulsing at the cavity fundamental frequency in Er/sup 3+/- and Nd/sup 3+/-fiber lasers with intracavity acousto-optic frequency shifters. A numerical model based on the split step Fourier method suggests that this pulse mode of operation may be attributed to the Kerr-type nonlinearity of the optical fiber. >
TL;DR: In this article, a broad intracavity birefringent plate filter was used to reduce the sidebands of the soliton in passively mode-locked fiber soliton lasers.
Abstract: The periodic perturbations to the soliton in passively mode-locked fiber soliton lasers cause dispersive wave shedding, which lead to sharp spectral sidebands that limit pulse duration. By using a broad intracavity birefringent plate filter, the side-bands are greatly reduced, and the pulse duration is shortened. The filter also allows wavelength tuning, and a 43 nm continuous tuning range is demonstrated for pulses of 311-357 is duration in a fully self-starting diode pumped system. >
TL;DR: In this article, an erbium-doped silica-based planar waveguide amplifier integrated with a directional coupler which multiplexes the signal and pump light was achieved. But this was achieved with a low noise figure of 5.0 dB.
Abstract: A high gain of 27 dB is achieved in an erbium-doped silica-based planar waveguide amplifier integrated with a directional coupler which multiplexes the signal and pump light. A low noise figure of 5.0 dB is attained with the planar amplifier by using an integrated coupler which is formed of erbium-doped silica-based waveguides.
TL;DR: A single-mode Nd(3+)-doped tellurite glass fiber laser operating at 1.061 microm is described, believed to be the first demonstration of a single- mode fiber laser in tellurites glass.
Abstract: A single-mode Nd(3+)-doped tellurite glass fiber laser operating at 1.061 microm is described. We believe this is the first demonstration of a single-mode fiber laser in tellurite glass. A lasing threshold of 27 mW of 818-nm absorbed pump power and a slope efficiency output power versus pump power of 23% emitted from one end were observed in the fiber cavity with 11.9% Fresnel reflection at both ends.
TL;DR: In this paper, the authors describe a programmable delay line that generates up to 50 ns of true time-delay in discrete 10 ns intervals, using an externally modulated wavelength tunable fiber laser and a six-element wavelength multiplexed fiber Bragg grating array, with the grating spacing set to yield the desired delay.
Abstract: This paper describes a novel programmable delay line that generates up to 50 ns of true time-delay in discrete 10 ns intervals. The delay line consists of an externally modulated wavelength tunable fiber laser and a six-element wavelength multiplexed fiber Bragg grating array, with the grating spacing set to yield the desired delay. >
Patent•
18 Aug 1994
TL;DR: In this article, a laser optical fiber probe has a silica fiber core with an end terminating in an inclined surface, and a capsule encloses the fiber and locates the end of the fiber in a gas chamber.
Abstract: A laser optical fiber probe has a silica fiber core with an end terminating in an inclined surface. A silica capsule encloses the end of the fiber and locates the end of the fiber in a gas chamber. Localized heat fuses the end of the fiber opposite the inclined surface to the capsule thereby eliminating secondary light reflections.
TL;DR: A linewidth-narrowing mechanism in lasers by nonlinear absorptive wave mixing of the counterpropagating beams in the cavity is proposed and a demonstration of the effect with an erbium-doped fiber laser is reported.
Abstract: We propose a linewidth-narrowing mechanism in lasers by nonlinear absorptive wave mixing of the counterpropagating beams in the cavity. We give a theoretical analysis and report on a demonstration of the effect with an erbium-doped fiber laser. The system also exhibits bistability in the dependence of the oscillation intensity versus pump power.
TL;DR: In this paper, the laser performance at 491 and 635nm of praseodymium-doped fluorozirconate fiber pumped at 1.01µm and 835nm is described and is interpreted with analytical solutions to the rate equations.
Abstract: The laser performance at 491 and 635nm of praseodymium-doped fluorozirconate fiber pumped at 1.01µm and 835nm is described and is interpreted with analytical solutions to the rate equations. Spectroscopic measurements of the absorption and the emission cross sections are presented, and the values are shown to be consistent with the observed lasing performance. The analytical model is shown to be a reliable indication of the optimum length of fiber for operation on the three-level 491nm transition.