Showing papers on "Saturable absorption published in 1994"
TL;DR: It is experimentally demonstrate that two chaotic passive Q-switched lasers can be synchronized by modulating the saturable absorber in the cavity of one laser with the output of the other laser.
Abstract: We experimentally demonstrate that two chaotic passive Q-switched lasers can be synchronized by modulating the saturable absorber in the cavity of one laser with the output of the other laser. The entrainment of the chaotic motion takes place when the slave system has a slightly different strange attractor from that of the master system. The observed synchronized pulsation of the two lasers is well reproduced by the computer simulation based on our rate-equation model.
177 citations
TL;DR: In this paper, the authors present a quantitative discussion of A-FPSA mode locking and compare it with other passive mode locking techniques such as KLM (Kerr Lens Mode locking).
Abstract: Passively mode-locked diode-pumped solid-state lasers can provide practical high-power laser sources with pico- and femtosecond pulse durations. We use semiconductors not only to optically pump but also to cw mode-lock or Q-switch a solid-state laser. A novel saturable absorber design, the Antiresonant Fabry-Perot Saturable Absorber (A-FPSA), allows of using semiconductor saturable-absorber materials even though they are generally not well-matched to the characteristics required for diode-pumped solid-state lasers, i.e., the semiconductors tend to have too much optical loss, a too low saturation intensity, and a too low damage threshold. This paper gives an overview of passively mode-locked ion-doped crystalline solid-state lasers. In particular, we present a quantitative discussion of A-FPSA mode locking, and compare A-FPSA mode locking with other passive mode locking techniques such as KLM (Kerr Lens Mode locking).
168 citations
TL;DR: In this paper, the dynamic and steady-state processes of the reverse saturable absorption (RSA) and the related optical limiting (OL) and optical bistability (OB) in metallophthalocyanine have been studied in detail using rate equations and the light-propagation equation.
Abstract: The dynamic and steady-state processes of the reverse saturable absorption (RSA) and the related optical limiting (OL) and optical bistability (OB) in metallophthalocyanine have been studied in detail using rate equations and the light-propagation equation. The experiments for demonstrating RSA, OL, and OB in a copper phthalocyanine (CuPc) solution with a Q-switched, frequency-doubled neodymium-doped yttrium-aluminum-garnet (Nd:YAG) laser were accomplished. The experimental results were consistent with the dynamic theoretical simulations, also approximately in accordance with the expression of RSA derived from the same equations at the steady-state condition.
167 citations
TL;DR: In this article, the dynamic processes of reverse saturable absorption (RSA) in a solution of C60 are studied in detail by use of rate equations and the light-propagation equation for a five-energy-level model.
Abstract: The dynamic processes of reverse saturable absorption (RSA) in a solution of C60 are studied in detail by use of rate equations and the light-propagation equation for a five-energy-level model. The RSA experimental results for C60 in toluene solution with a nanosecond–picosecond Nd:YAG laser at 532 nm are consistent with the theoretical simulations. Effects of sample concentration and thickness on RSA and contributions of the singlet and triplet excited states to RSA for various laser-pulse widths and wavelengths are also analyzed. Finally, an all-optical switch based on excited-state nonlinear absorption and the pump-probe technique is implemented.
109 citations
TL;DR: In this paper, the results of investigations of emission, saturable absorption, and lasing properties of YAG: Cr4+ crystal are summarized and analyzed, and a spectroscopic and thermodynamic model of the dopant center is developed.
101 citations
TL;DR: In this paper, the authors compared the response of bulk and single quantum well absorbers at different reverse bias levels and pump powers, and found an ultrafast transient in the response, followed by a slower rise before the final recovery.
Abstract: Absorption recovery dynamics of GaAs/AlGaAs field‐enhanced waveguide saturable absorbers are studied by pump‐probe differential transmission measurements. We compare the response of bulk and single quantum well absorbers at different reverse bias levels and pump powers, and find an ultrafast transient in the response, followed by a slower rise before the final recovery. The absorption fully recovers after a few picoseconds, which is an important result for mode‐locked lasers.
92 citations
TL;DR: A self-starting passively mode-locked diode-pumped Cr:LiSAF laser, achieving pulses as short as 98 fs with an average power as high as 50 mW with tunability of 100 nm FWHM is demonstrated.
Abstract: We demonstrate a self-starting passively mode-locked diode-pumped Cr:LiSAF laser, achieving pulses as short as 98 fs with an average power as high as 50 mW. In continuous-wave operation, we demonstrate 140 mW of output power with a tunability of 100 nm FWHM. These results were achieved by use of lower Cr3+ doping (1.5%), high-brightness diode lasers pumping from both sides of the crystal, and a low-loss antiresonant Fabry–Perot saturable absorber to start and sustain mode-locked operation.
90 citations
TL;DR: In this article, an erbium-doped fiber laser with an intracavity nonlinear absorptive wave mixing of the counter propagating beams was used to obtain linewidth of the order of a few kilohertz.
Abstract: Narrow-linewidth, single longitudinal mode operation is demonstrated in an erbium-doped fibre laser with an intracavity nonlinear absorptive wave mixing of the counter propagating beams. An unpumped length of erbium-doped fibre serves as the saturable absorber. Linewidths of the order of a few kilohertz are obtained.
87 citations
TL;DR: In this paper, a nonlinear loop mirror can be used as a solid state saturable loss element, and the implications for its use in a laser cavity are discussed, as well as its transmission characteristics when used in the soliton-forming wavelength range.
Abstract: A nonlinear loop mirror can be used as a solid state saturable loss element. The transmission characteristics of the different embodiments of this mirror are shown to change significantly when it is used in the soliton-forming wavelength range. The implications for its use in a laser cavity are discussed. >
86 citations
TL;DR: The stability of passively mode-locked fiber lasers with fast saturable absorption is examined by a direct numerical approach, which retains the advantage of previous analytical research of permitting one to explore a wide range of parameter space while also allowing one to avoid approximations in the stability calculation.
Abstract: The stability of passively mode-locked fiber lasers with fast saturable absorption is examined by a direct numerical approach. The laser operation is described by use of a standard model, closely related to the Ginzburg–Landau equation, which is valid when the change of the laser pulse during one round trip through the laser is small. This equation is then linearized around an equilibrium solution, and the eigenmodes and eigenvalues of the linearized equation are determined numerically. This approach retains the advantage of previous analytical research of permitting one to explore a wide range of parameter space while also permitting one to avoid approximations in the stability calculation. The stability of a figure-eight loop laser with the amplifier in the external loop is then studied by use of this approach.
79 citations
Patent•
01 Mar 1994TL;DR: In this article, a CPM mode-locked fiber ring laser including an ion-implanted semiconductor saturable absorber providing sub-picosecond pulses at rapid repetition rates is presented.
Abstract: A CPM mode-locked fiber ring laser including an ion-implanted semiconductor saturable absorber providing sub-picosecond pulses at rapid repetition rates. The laser provides compact, turn-key capability and is polarization insensitive.
Patent•
28 Nov 1994TL;DR: In this paper, a new class of solid state laser crystals and lasers are formed of transition metal doped sulfide, selenide, and telluride host crystals which have four fold coordinated substitutional sites.
Abstract: A new class of solid state laser crystals and lasers are formed of transition metal doped sulfide, selenide, and telluride host crystals which have four fold coordinated substitutional sites. The host crystals include II-VI compounds. The host crystal is doped with a transition metal laser ion, e.g., chromium, cobalt or iron. In particular, Cr 2+ -doped ZnS and ZnSe generate laser action near 2.3 μm. Oxide, chloride, fluoride, bromide and iodide crystals with similar structures can also be used. Important aspects of these laser materials are the tetrahedral site symmetry of the host crystal, low excited state absorption losses and high luminescence efficiency, and the d 4 and d 6 electronic configurations of the transition metal ions. The same materials are also useful as saturable absorbers for passive Q-switching applications. The laser materials can be used as gain media in amplifiers and oscillators; these gain media can be incorporated into waveguides and semiconductor lasers.
TL;DR: In this article, the authors presented a Q-switching algorithm for Nd:YAG, Nd.YAlO3, and nd:KGW laser oscillators with a Cr4+YAG as saturable absorber, and obtained transverse mode polarized light pulses with energies of 50 mJ and repetition rates 10 Hz.
Abstract: Q-switching of Nd:YAG, Nd:YAlO3, Nd:KGW laser oscillators with a Cr4+:YAG as saturable absorber is reported. Transverse mode polarized light pulses with energies of 50 mJ and repetition rates 10 Hz are obtained.
TL;DR: In this article, the authors studied nonlinear absorption at 532 nm in a cadmium texaphyrin solution using 8 ns and 23 ps laser pulses and showed that reverse saturable absorption occurs only at low fluences, and the transmission increases with increasing incident fluence at high fluences.
Abstract: Nonlinear absorption at 532 nm in a cadmium texaphyrin solution has been studied using 8 ns and 23 ps laser pulses. The experiments show that reverse saturable absorption occurs in the nanosecond case. For picosecond pulses, reverse saturable absorption occurs only at low fluences, and the transmission increases with increasing incident fluence at high fluences. A six‐level model is presented to explain these nonlinear absorption effects. Several photophysical parameters for cadmium texaphyrin, such as absorption cross sections at 532 nm and lifetimes, have been evaluated by theoretical simulations of the experimental results.
TL;DR: In this article, the authors present an analysis for self-focusing of an elliptic Gaussian laser beam in a saturable nonlinear medium and show that stationary self-trapped propagation is forbidden in such a medium.
Abstract: We present an analysis for self-focusing of an elliptic Gaussian laser beam in a saturable nonlinear medium. It is shown that stationary self-trapped propagation is forbidden in a saturable medium. Though self-trapped propagation does not occur, a virtual threshold power for self-focusing can be defined. Above this threshold power value, but not far from it, the beam focuses. Below this threshold the beam defocuses. It is also shown that the effective beam radius never reaches zero, which is a property of a Gaussian laser beam.
TL;DR: Saturable absorber Q switching of the Er:glass laser at 1533 nm using U4+:SrF2 has been obtained using a 2.69mm-thick Q switch in a 14 cm−long plane-parallel cavity, with a 3×50 mm Kigre QE•7S er:glass rod as discussed by the authors.
Abstract: Saturable absorber Q switching of the Er:glass laser at 1533 nm using U4+:SrF2 has been obtained. Q‐switched pulses of 3 mJ and 60 ns full width at half‐maximum were achieved using a 2.69‐mm‐thick Q switch in a 14‐cm‐long plane‐parallel cavity, with a 3×50 mm Kigre QE‐7S Er:glass rod. The high absorption cross section of U4+:SrF2 resulted in efficient Q‐switched operation (without intracavity focusing) in agreement with the theoretical predictions.
Patent•
14 Nov 1994
TL;DR: In this paper, a self-aligned, monolithic, solid microlaser with passive switching by a saturable absorber and a production process therefor is presented, in which the cavity for the micro-laser has a solid active medium, a saturated absorber, an entrance mirror and an exit mirror.
Abstract: A self-aligned, monolithic, solid microlaser with passive switching by a saturable absorber and a production process therefor. The cavity for the microlaser has a solid active medium, a saturable absorber, an entrance mirror and an exit mirror, wherein the saturable absorber is a thin film of saturable absorbent material directly deposited on the solid active medium.
Patent•
07 Dec 1994TL;DR: In this article, a polarization-insensitive fiber laser with a pair of 45 degree Faraday rotators on either end of the fiber gain source is modeled as a self-starting, polarization insensitive modelocked laser.
Abstract: A polarization insensitive fiber laser. A pair of 45 degree Faraday rotators are positioned on either end of the fiber gain source. The resulting laser is insensitive to external perturbations with respect to known entrance and exit polarization states of the laser light. Modelocking, both passive and active, is possible. Configuration wherein the fiber is a combination of polarization preserving and Erbium-doped, and a saturable absorber is included provide a self-starting, polarization insensitive modelocked laser.
Patent•
14 Nov 1994
TL;DR: In this article, a laser cavity with passive switching by a saturable absorber and a laser incorporating the cavity is presented, where the saturable material is a thin film of saturable absorbing material directly deposited on the solid, active medium.
Abstract: A laser cavity with passive switching by a saturable absorber and a laser incorporating the cavity. The laser cavity has a solid, active material saturable absorber, an entrance mirror and an exit mirror. The saturable absorber is a thin film of saturable absorber material directly deposited on the solid, active medium. The laser incorporates such cavity and a mechanism for pumping the cavity.
TL;DR: In this article, a single Q-switched laser pulse of 11 mJ in energy and ∼45 ns in duration at 80 J flashlamp input energy was obtained at room temperature.
Abstract: Passive Q‐switching of the flashlamp pumped Tm,Cr:Y3Al5O12 2‐μm laser with a Ho:YLiF4 saturable absorber has been demonstrated at room temperature. A single Q‐switched laser pulse of 11 mJ in energy and ∼45 ns in duration at 80 J flashlamp input energy was obtained. The wavelength of the Q‐switched laser output pulse and the Tm,Cr:Y3Al5O12 free‐running output was 2.017 μm.
TL;DR: In this paper, the spatio-temporal behavior of the electric field inside a laser with saturable absorber in the good cavity limit was studied and it was shown that the underlying nonlinear partial differential equation admits stable spatially localized solutions for both the one and the two-dimensional case.
Abstract: We study the spatio-temporal behavior of the electric field inside a laser with saturable absorber in the good cavity limit. We find that the underlying nonlinear partial differential equation admits stable spatially localized solutions for both the one- and the two-dimensional case. We critically examine similarities and differences with the localized solutions found recently near a weakly inverted bifurcation to traveling waves.
Patent•
14 Nov 1994
TL;DR: In this paper, a self-aligned monolithic solid-state microlaser with passive Q-switching by saturable absorber and its method of manufacture is described, which is characterized by a thin film of saturable absorbent material deposited directly onto the solid active medium.
Abstract: Self-aligned monolithic solid-state microlaser with passive Q-switching by saturable absorber and its method of manufacture. This laser cavity for a microlaser includes a solid active medium (8), a saturable absorber (12, 22), an input mirror (13) and an output mirror (15), and is characterized in that the saturable absorber is a thin film of saturable absorbent material deposited directly onto the solid active medium.
TL;DR: In this paper, the authors show that by inserting nonlinear optical loop mirrors into an optical fiber transmission line, 1.5 ps solitons can be transmitted over at least 750 km, with amplifiers spaced at 15 km intervals.
Abstract: The authors show that by inserting nonlinear optical loop mirrors into an optical fibre transmission line, 1.5 ps solitons may be transmitted over at least 750 km, with amplifiers spaced at 15 km intervals.
Patent•
11 Mar 1994
TL;DR: In this paper, a single solid-state optical element (10) is integrated into an undoped substrate (14) having front and rear surfaces disposed at a predetermined angle, and a dielectric coating (15) (mirror) on the back surface of the optical element provides 100% reflectivity.
Abstract: Saturable absorption, polarization, and retroreflection are integrated into a single solid-state optical element (10). The optical element (10) comprises an undoped substrate (14) having front and rear surfaces disposed at a predetermined angle. A dielectric coating (15) is disposed on the rear surface of the substrate (14), and at least one saturable absorber platelet (11) is disposed on the front surface of the substrate (14). The saturable absorbing species used in the platelet(s) (11) are either F₂⁻ color-centers in lithium fluoride or Cr⁴⁺ dopant ions in one of several suitable host optical materials. Linear polarization of the laser beam (13a) is achieved by orienting the input face of the optical element (10) at Brewster's angle. The dielectric coating (15) (mirror) on the back surface of the optical element (10) provides 100% reflectivity. The optical element (10) is a monolithic, simple to fabricate, easy to align multi-functional element for use in a laser resonator (12). The optical element (10) provides passive Q-switching, discrimination for linear polarization, and laser beam reflection. The mirror is an integral part of the optical element (10), and it is easy to align the integrated polarizer. By aligning the optical element (10) for retroreflection, the Brewster's angle condition is automatically met and optimal polarization discrimination is achieved. The optical element (10) improves the quality and efficiency of lasers in which it is employed. The present invention is easy to align and reduces the number of optical elements in the laser, thereby improving system reliability.
TL;DR: In this article, the authors used a CuInS2xSe2(1−x)doped glass as an intracavity saturable absorber, and achieved ultrashort laser pulses with duration of 16 ps and 36 ps, respectively.
Abstract: By using a CuInS2xSe2(1−x)‐doped glass as an intracavity saturable absorber, passive mode‐locking of Nd:YAG and Nd:YAlO3 lasers is obtained. Ultrashort laser pulses are achieved with duration of 16 ps (for Nd:YAlO3 at 1.08 μm) and 36 ps (for Nd:YAG at 1.064 μm), respectively. The intensity dependent transmittance and transient absorption change measurements are performed on CuInS2xSe2(1−x)‐doped glasses at 1.08 μm with the use of laser pulses of 15 ps width. The bleaching relaxation time is found to be ∼11 ps.
TL;DR: In this paper, the authors demonstrated clock decision, retiming and pulse shaping as well as wavelength conversion at 2.5 and 5 Gbit/s with bistable semiconductor lasers.
Abstract: Clocked decision, retiming and pulse shaping as well as wavelength conversion (32 nm) is demonstrated at 2.5 and 5 Gbit/s with bistable semiconductor lasers. It is also shown that switching is possible at 10 Gbit/s using the same mechanism.
TL;DR: In this article, the temporal and spatial behavior of resonant optical waveguide (ROW) arrays with significant interelement loss reveal the presence of sustained self-pulsations in the output intensity of the laser.
Abstract: Measurements of the temporal and spatial behavior of resonant optical waveguide (ROW) laser arrays with significant interelement loss reveal the presence of sustained self‐pulsations in the output intensity of the laser. The mechanism responsible for pulsations is believed to be saturable absorption arising from the presence of absorbers in the interelement regions. This is experimentally confirmed in that reduction or elimination of the interelement loss suppresses the pulsations. Quiescent behavior is obtained to at least 0.45 W continuous wave power and 3.4 times threshold in near‐diffraction‐limited beams from devices with negligible interelement loss.
TL;DR: In this article, the density matrix equations of motion for a six-level model are deduced to explain these nonlinear absorption effects, and numerical results calculated by the model agree well with the experimental results.
Patent•
19 Jan 1994
TL;DR: In this article, a monolithic self-Q-switched laser with a distributed saturable absorber in the material provides a spectral stabilization mechanism that ensures single longitudinal mode operation.
Abstract: A monolithic self-Q-switched laser generates laser pulses with short duration, high peak power, a single longitudinal mode, and extremely small pulse-to-pulse intensity fluctuations. The laser comprises of a length of solid-state laser material with a plurality of dopants, so that the material can generate coherent radiation for laser action and, in the same material, provide saturable absorption at the wavelength of the laser emission necessary for Q-switching. The distributed saturable absorber in the material provides a spectral stabilization mechanism that ensures single longitudinal-mode operation. The laser cavity is formed by the two end surfaces of the solid-state laser material with appropriate reflectivity coatings. When the laser material is pumped above the threshold condition, the laser device produces short pulses having high peak power in a single longitudinal mode and single transverse mode.