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Showing papers on "Signal beam published in 1997"


Journal ArticleDOI
TL;DR: Coherent amplification of a signal beam by a strong pump beam is observed in thin films of fullerene-doped nematic liquid crystal using electro-optically induced spatially reorientation of the liquid-crystal axis and the resultant phase-shifted index grating required for two-beam coupling.
Abstract: Coherent amplification of a signal beam by a strong pump beam is observed in thin films of fullerene-doped nematic liquid crystal. Exponential gain constants as high as 2890 cm-1 with no phase cross talk are achieved at low applied dc bias voltage and pump beam intensity. The underlying mechanism is the electro-optically induced spatially reorientation of the liquid-crystal axis and the resultant phase-shifted index grating required for two-beam coupling.

107 citations


Journal Article
TL;DR: In this article, a new photopolymer holographic recording material, ULSH-500, based on cationic ring-opening polymerization, has been further optimized to achieve low transverse shrinkage without sacrificing sensitivity.
Abstract: A new photopolymer holographic recording material, ULSH-500, based on cationic ring-opening polymerization, has been further optimized to achieve low transverse shrinkage without sacrificing sensitivity. The extent of transverse (z) and lateral (x) shrinkage was determined explicitly in this study for a range of slant angles in volume holograms recorded to near saturation and in holograms of low diffraction efficiency. The values ΔK x /K x and ΔK z /K z , which represent the physical material shrinkage in the grating vector plane, were ascertained by (1) direct measurement of the differential angle changes in the reference and signal beam angles necessary to achieve Bragg matching and (2) measurement of the average refractive index. The accuracy of this method was primarily limited by the exactness in determining the angle of peak efficiency in the Bragg selectivity curve. It is demonstrated that the peak angle can be established to within a small fraction of a degree. It is shown that the assumption of anchoring and, thus, uniaxial shrinkage as embodied in the conventional fringe rotation model cannot be applied for the photopolymer ULSH-500 under the recording conditions used herein. It is demonstrated that background uplift in angular selectivity profiles can be attributed to nonuniformity in the grating strength throughout the transverse direction of the recording media, and that the uplift can be reduced to negligible levels by using a low fluence pre-imaging exposure. Calorimetric analysis of reaction kinetics was performed using direct laser irradiation delivered by optical fiber.

92 citations


Journal ArticleDOI
TL;DR: It is shown that the diffraction of a pump beam in the direction of a weak signal leads to a net amplification of the signal beam, with no need for a phase shift between the interference pattern and the induced index grating.
Abstract: A new two-wave-mixing interaction with gain through a Bi12SiO20 liquid-crystal light valve is presented. We show that the diffraction of a pump beam in the direction of a weak signal leads to a net amplification of the signal beam, with no need for a phase shift between the interference pattern and the induced index grating. A two-wave-mixing gain of 10 and a 150-ms response time are obtained with a 8.8-µm-thick liquid-crystal layer, a total intensity of the interacting beams of only 200 µW/cm2, and an ac external voltage of ±6 V. Image amplification is also demonstrated.

78 citations


Patent
10 Jun 1997
TL;DR: In this article, a laser absorption sensor system for performing optical measurements on a sample is described, which includes a tunable laser, capable of being tuned at rates exceeding 1 KHZ, and with a tuning range approaching 1 GHz.
Abstract: A laser absorption sensor system for performing optical measurements on a sample is described. The sensor system includes a tunable laser, capable of being tuned at rates exceeding 1 KHZ, and with a tuning range approaching 1 GHz. The laser beam is modulated at a modulation frequency between 1 and 100 KHz. Modulation in this frequency range is termed wavelength modulation. The beam is split into two beams, a signal beam and a reference beam. The signal beam traverses the sample where characteristic absorption takes place and is incident on a signal photodetector. The reference beam is incident directly on a reference photodetector. A noise cancellation circuit combines signal and reference photo-currents from signal and reference photodetectors reducing signal noise and increasing system sensitivity. The combination of wavelength modulation and the noise cancellation scheme provide a highly sensitive simple, rugged, low cost laser absorption sensor system.

50 citations


Patent
04 Dec 1997
TL;DR: In this paper, a system and method for performing selected optical measurements on a sample is provided utilizing an optical coherence domain reflectometer which includes a diffraction grating, where a broad band light source produces light having a short coherence length.
Abstract: A system and method for performing selected optical measurements on a sample is provided utilizing an optical coherence domain reflectometer which includes a diffraction grating. A broad band light source produces light having a short coherence length. A beamsplitter splits the light into a signal beam and a reference beam. A reference mirror is disposed to receive the reference beam. A lens brings the signal beam to focus on the sample. A diffraction grating receives a reflection from the sample and from the reference mirror, the reflections being incident on the diffraction grating with respect to said diffraction grating normal such that the positive and negative first or second or higher diffraction orders from said reflections received propagate along a normal to said diffraction grating. A lens collects the diffracted orders from the diffraction grating and brings the diffracted orders to focus on a detector, the detector producing an output of said positive and negative first diffracted orders received. A computer processes the output from the detector.

49 citations


Patent
Yoshinori Tanaka1, Shuji Kobayakawa1, Hiroyuki Seki1, Takeshi Toda1, Masafumi Tsutsui1 
19 Dec 1997
TL;DR: In this article, a multistage interference cancellation system for CDMA (Code Division Multiple Access) multibeam-antenna communication system is presented. But the system is not suitable for wireless networks.
Abstract: A multistage interference canceller equipment and interference canceller method for use, for example, in CDMA (Code Division Multiple Access) multibeam-antenna communication system includes in each stage an interference canceller unit which has a replica signal generator which generates from an input beam signal a first interference replica signal and outputs a first error signal, and an interference removal unit which receives from another replica signal generator a second interference replica signal, multiplies that second interference replica signal by conversion coefficients and subtracts an obtained signal from the first interference replica signal to produce a second error signal so that an error signal is generated for each signal beam from the interference replica signals of a local signal beam and other signal beams to eliminate interference.

48 citations


Journal ArticleDOI
TL;DR: The parametric generation of broad spectral bandwidths by the use of suitable phase-matching geometries is reported and a tunable bandwidth of >100 nm is demonstrated.
Abstract: The parametric generation of broad spectral bandwidths by the use of suitable phase-matching geometries is reported. Greater than 100-nm simultaneous bandwidth in the visible is generated in a collimated signal beam from a novel, noncollinear phase-matching geometry in a β-barium borate optical parametric oscillator, which is pumped by the collimated output of a Q-switched and frequency-tripled Nd:YAG laser. Dispersive cavity tuning of the optical parametric oscillator by use of a rotatable Littrow-mounted grating, with a static crystal and pump configuration, is also described. A tunable bandwidth of >100 nm is also demonstrated.

32 citations


Journal ArticleDOI
TL;DR: The effect of aberrations on heterodyne efficiency is demonstrated by including Seidel aberration in the mixing of two perfectly matched gaussian beams and extension to propagation through lidar optical systems is discussed.
Abstract: Heterodyne efficiency of a coherent lidar system reflects the matching of phase and amplitude between a local oscillator (LO) beam and received signal beam and is, therefore, an indicator of system performance. One aspect of a lidar system that affects heterodyne efficiency is aberrations present in optical components. A method for including aberrations in the determination of heterodyne efficiency is presented. The effect of aberrations on heterodyne efficiency is demonstrated by including Seidel aberrations in the mixing of two perfectly matched gaussian beams. Results for this case are presented as animations that illustrate the behavior of the mixing as a function of time. Extension of this method to propagation through lidar optical systems is discussed.

29 citations


Patent
04 Dec 1997
TL;DR: In this article, a system for performing selected optical measurements on a sample is provided utilizing an optical coherence domain reflectometer which includes a diffraction grating (G) and a broadband light source (13) produces light having a short coherence length.
Abstract: A system (11) and method for performing selected optical measurements on a sample is provided utilizing an optical coherence domain reflectometer which includes a diffraction grating (G). A broadband light source (13) produces light having a short coherence length. A beam splitter (BS1) splits the light into a signal beam and a reference beam. A reference mirror (M5) is disposed to receive the reference beam. A lens (O1) brings the signal beam to focus on the sample. A diffraction grating (G) receives a reflection from the sample and from the reference mirror, the reflections being incident on the diffraction grating with respect to said diffraction grating normal such that the positive and negative first or second or higher diffraction orders from said reflections received propagate along a normal to said diffraction grating. A lens (L1) collects the diffracted orders from the diffraction grating and brings the diffracted orders to focus on a detector (23), the detector (23) producing an output of said positive and negative first diffracted orders received. A computer (25) processes the output from the detector (23).

25 citations


Patent
04 Apr 1997
TL;DR: In this paper, the outputs of several amplification modules are combined into a single output beam using adaptive optics, with the outputs from different modules phase matched to each other by diverting two minor portions of the combined beam, partially overlapping the diverted beams and adjusting the amplification module phases to cancel phase differentials between the overlapped portions.
Abstract: An optical amplification system directs a diffraction-limited signal beam through a series of approximately 90° crossings with a number of non-diffraction-limited pump beams in a photorefractive medium All of the beams are s-polarized, resulting in an energy transfer from the pumps to the signal beam while leaving the signal beam diffraction-limited The photorefractive medium is preferably a series of BaTiO 3 :Rh crystals that receive the pump and signal beams through orthogonal faces, with their C-axes at approximately 45° to both beams A binary tree optical distribution network is used to minimize waveguide splits in forming a large number of pump beams The outputs of several amplification modules are combined into a single output beam using adaptive optics, with the outputs from the different modules phase matched to each other by diverting two minor portions of the combined beam, partially overlapping the diverted beams and adjusting the amplification module phases to cancel phase differentials between the overlapped portions Similarly, sets of combined and phase-matched beams can be combined with each other (again using adaptive optics) to generate still higher powers using a super module approach

20 citations


PatentDOI
TL;DR: In this paper, a single-unit 90°-hybrid coherent detection system is proposed to provide simultaneous phase and polarization diversity by combining the polarization angle and the phase angle of the input lightwave signal into an effective phase angle in the hybrid output.

Journal ArticleDOI
TL;DR: A new novelty optical filter that uses a bacteriorhodopsin film based on the time-dependent nonlinear diffraction efficiency of real-time holograms recorded in the film to enhance only leading edges of moving patterns.
Abstract: We propose a new novelty optical filter that uses a bacteriorhodopsin film. This filter is based on the time-dependent nonlinear diffraction efficiency of real-time holograms recorded in the film. As soon as the signal beam carrying a pattern is diffracted by the polarization hologram recorded in the bacteriorhodopsin film, it begins to erase the hologram and suppresses the diffraction of the beam at the position of the stationary part of the pattern. This filter enhances only leading edges of moving patterns. In this system undesired scattered light, which is orthogonally polarized to the diffracted beam, is discriminated by a polarizer.

Patent
02 Dec 1997
TL;DR: In this article, the authors proposed a beamforming scheme to encode individual user signals in such a way as to enable the switching processing of the signal relay to be implemented at the beam level rather than at the user level.
Abstract: Each user signal of a communications network is encoded using a narrowband traffic code and a wideband cover code for transmission to a signal relay (e.g., a communications satellite) in one of a plurality of uplink signal beams. The signal relay receives all of the user signals in the different uplink signal beams and processes them to re-transmit them in different downlink signal beams to their different appropriate destinations. The narrowband traffic codes and wideband cover codes are selected to encode the individual user signals in such a way as to permit the switching processing of the signal relay to be implemented at the beam level (e.g., individual components processing multiple user signals at a time) rather than at the user level (e.g., one switching circuit for each user). For example, in one embodiment, all user signals within the same signal beam are encoded using different narrowband codes and the same wideband cover code, while user signals in different signal beams are encoded using different wideband cover codes. The present invention enables a reduction in the volume and cost of switching equipment within the signal relay. Furthermore, much of the switching processing can be implemented at intermediate frequencies (IF) using conventional, relatively inexpensive radio frequency (RF) components.

Proceedings ArticleDOI
15 May 1997
TL;DR: In this paper, the extent of transverse (z) and lateral (x) shrinkage was determined explicitly for a range of slant angles, in volume holograms which were recorded to near saturation and in holograms of low diffraction efficiency.
Abstract: A new photopolymer holographic recording material, ULSH-500, based on cationic ring-opening polymerization, has been further optimized to achieve low transverse shrinkage without sacrificing sensitivity. The extent of transverse (z) and lateral (x) shrinkage was determined explicitly in this study for a range of slant angles, in volume holograms which were recorded to near saturation and in holograms of low diffraction efficiency. (Delta) Kx/Kx and (Delta) Kz/Kz, which represent the physical material shrinkage in the grating vector plane, were ascertained by (1) direct measurement of the differential angle changes in the reference and signal beam angles necessary to achieve Bragg matching and (2) measurement of the average refractive index. The accuracy of this method was primarily limited by the exactness in determining the angle of peak efficiency in the Bragg selectivity curve. It is demonstrated that the peak angle can be established to within a small fraction of a degree. It is shown that the assumption of anchoring and thus uniaxial shrinkage, as embodied in the conventional fringe rotation model, cannot be applied for the photopolymer, ULSH-500, under the recording conditions used herein.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Patent
Alain Gaillard1, Stephan Schmitz1
12 Feb 1997
TL;DR: In this article, it was shown that the transmitting and receiving device can be arranged in the lamp chamber of an illumination device such that by the lamp glass of the special signal beam (a, B, C) can be emitted or receivable.
Abstract: In a motor vehicle having attached to a body of the illumination device with at least one lamp (3) and a reflector (1) in a lamp room and the air space to the outside final lamp glass (2), on the outside of a cleaning device may be attached and with a transmission - and / or receiving device (4) for emitting and / or receiving special signal beams (A, B, C), the transmitting and / or receiving device (4) can be small-sized and non-irritating to arrange in that the transmitting and / or is the receiving device (4) arranged in the lamp chamber of an illumination device such that by the lamp glass (2) of the special signal beam (a, B, C) can be emitted or receivable.

Patent
29 Oct 1997
TL;DR: In this paper, a loop four-wave mixing phase conjugator for depolarized signal beams is presented. But the authors do not consider the effect of the optical diode and gain medium on the optical loop.
Abstract: A loop four-wave mixing phase conjugator that can be used with depolarized signal beams comprises a polarization separator (10), a polarization mixer (19), an optical diode (20), a gain medium (22) and relay optics (14, 16) that together form a unidirectional laser resonator. In operation, the polarization separator separates a signal beam (e1) into orthogonally polarized signal beam components (e11) and (e12) and directs them to a nonlinear medium (12). The components propagate through the nonlinear medium and emerge as loop beam (e2), with orthogonally polarized components (e21) and (e22). The polarization mixer mixes the energy from the two orthogonally polarized loop beam components, and relay optics direct the loop beam components back to the nonlinear medium at an angle with respect to the input beam. The loop beam components intersect and optically interfere with signal beam components (e11) and (e12) in the nonlinear medium to form gratings (18). The optical diode and gain medium are positioned in the optical loop so that an oscillation beam (e3) builds up from optical noise in the resonator and oscillates in a direction counter to the propagation direction of loop beam components (e21) and (e22). A portion of oscillation beam (e3) is transmitted by the gratings, and exits the optical loop as an output beam (e4). (e3) is phase conjugate to the input beam (e1) in both the spatial and polarization senses.

Journal ArticleDOI
TL;DR: In this article, a four-wave mixing technique for the measurement of circular dichroism in optically active liquid samples is demonstrated, where two cross-polarized continuous-wave laser beams are crossed at a small angle in a cyclic dichroic liquid, and a weak thermal grating is produced with a phase depending on the sign of the circular dichroidism.
Abstract: A novel four-wave mixing technique for the measurement of circular dichroism in optically active liquid samples is demonstrated. When two cross-polarized continuous-wave laser beams are crossed at a small angle in a circular dichroic liquid, a weak thermal grating is produced with a phase depending on the sign of the circular dichroism. The polarization of one of the beams can be modified to allow coherent interference with an intensity grating-induced thermal grating. A probe beam scattering from the composite grating results in a coherent signal beam that reveals the sign and the magnitude of analyte circular dichroism. The use of this technique to optimize the signal-to-noise ratio in the presence of scattered light and laser noise is discussed.

Patent
Shuji Kobayakawa1, Hiroyuki Seki1, Yoshinori Tanaka1, Takeshi Toda1, Masafumi Tsutsui1 
16 Dec 1997
TL;DR: In this article, a multistage interference cancellation system for CDMA (Code Division Multiple Access) multibeam-antenna communication system is presented. But the system is not suitable for wireless networks.
Abstract: A multistage interference canceller equipment and interference canceller method for use, for example, in CDMA (Code Division Multiple Access) multibeam-antenna communication system includes in each stage an interference canceller unit which has a replica signal generator which generates from an input beam signal a first interference replica signal and outputs a first error signal, and an interference removal unit which receives from another replica signal generator a second interference replica signal, multiplies that second interference replica signal by conversion coefficients and subtracts an obtained signal from the first interference replica signal to produce a second error signal so that an error signal is generated for each signal beam from the interference replica signals of a local signal beam and other signal beams to eliminate interference.

Patent
29 Oct 1997
TL;DR: In this paper, a compact loop four-wave mixing phase conjugator that can be used in practical optical applications comprises a reflective nonlinear cell (12), relay optics (2, 4, 6, 8), an optical gain medium (26), and an optical diode (24) that together form a circumference ring laser resonator.
Abstract: A compact loop four-wave mixing phase conjugator that can be used in practical optical applications comprises a reflective nonlinear cell (12), relay optics (2, 4, 6, 8), an optical gain medium (26), and an optical diode (24) that together form a unidirectional ring laser resonator. In operation, a signal beam (e 1 ) is directed to the nonlinear cell (12), where it passes through a nonlinear medium (14) contained within the cell and is reflected out of the cell as loop beam (e 2 ). The relay optics direct loop beam (e 2 ) through the optical diode (24), optical gain medium (38), and back to the nonlinear cell (12), where it intersects and optically interferes with the signal beam (e 1 ) to form a refractive index grating (22) in the nonlinear medium (14). The optical diode (24) and gain medium (38) are positioned in the loop so that an oscillation beam (e 3 ) builds up from optical noise in the resonator and oscillates in a direction counter to the propagation direction of loop beam (e 2 ). A portion of oscillation beam (e 3 ) is transmitted by the refractive index grating, reflects off the reflective portion (16) of the nonlinear cell (12) and emerges from the cell as phase conjugate output beam (e 4 ).

Journal ArticleDOI
TL;DR: In this article, a degenerate four-wave mixing in a three-dimensional, forward 4W mixing geometry for two-dimensional imaging of combustion species is reported. But it is not shown in this paper that the generated signal beam propagates in the direction that fulfills the phase match- ing condition and is spatially separated from the other beams.
Abstract: The use of degenerate four-wave mixing in a three-dimensional, forward four-wave mixing geometry for two-dimensional imaging of combustion species is reported. In this configuration, a beam of circular cross section inter- sects in the flame the crossing area of two beams that have been focused to form thin sheets of light. The generated signal beam propagates in the direction that fulfills the phase match- ing condition and, therefore, is spatially separated from the other beams. The thin intersection volume of the three beams is imaged onto a detector. Thus, information on the signal distribution in one plane in the sample can be recorded. The method is demonstrated with experiments performed on OH molecules in a premixed acetylene-oxygen flame.

Journal ArticleDOI
TL;DR: In this paper, a fiber optic heterodyne vibrometer configuration based on the use of birefringent optical fibre components is demonstrated with a laser diode at 833 nm with a minimum detectable phase change of obtained at 5 kHz.
Abstract: A fibre optic heterodyne vibrometer configuration based on the use of birefringent optical fibre components is demonstrated. The heterodyne processing is moved to the receiving section of the interferometer, reducing the optomechanical stability requirements of the system and enabling optimization of the reference to signal beam ratio intensity. The instrument can be configured to have minimum down lead sensitivity. The technique was demonstrated with a laser diode at 833 nm with a minimum detectable phase change of obtained at 5 kHz.

Journal ArticleDOI
TL;DR: In this article, a multichannel unbalanced homodyning method was proposed for measuring the density matrix of a single-mode optical field in the photon-number representation, combining the signal beam and the local oscillator by a hightransmittance beam splitter.
Abstract: Multichannel unbalanced homodyning is proposed for measuring the density matrix of a single-mode optical field in the photon-number representation. Combining the signal beam and the local oscillator by a hightransmittance beam splitter, the interfering field is detected using multichannel photocounting. The density matrix is determined by direct statistical sampling of the coincident events recorded for various values of the local-oscillator phase. The usefulness of the method is demonstrated by computer simulations of measurements including error estimations.

Patent
14 Feb 1997
TL;DR: In this article, a variable apex angle prism is used to align light beams between adjacent boards to adjust deviation with an optical system even when the position of the board is deviated.
Abstract: PROBLEM TO BE SOLVED: To provide an inter-board optical interconnection equipment capable of easily adjusting deviation with an optical system even when the position of board is deviated, and correctly aligning light beams between adjacent boards. SOLUTION: A variable apex angle prism 2-7 is arranged between adjacent boards 2-1 and the signal from light beam detection sensor 2-5 is fed back to the variable apex angle prism 2-7 so that an optical signal beam from a planar light emitting laser array 2-2 on one board can be made incident on any desired detector array 2-4 on the other board. Thus, the advancing direction of optical signal beam from the planar light emitting array 2-2 on one board to the detector array 2-4 on the other board is controlled through the variable apex angle prism.

Patent
09 Sep 1997
TL;DR: In this article, the authors proposed a method to return a beam quality to the original quality in a short time without laser beam source failure and suppress deterioration of life of laser beam sources by judging whether quality of a pulse beam is satisfactory or not.
Abstract: PROBLEM TO BE SOLVED: To return a beam quality to the original quality in a short time without laser beam source failure and suppress deterioration of life of laser beam source, by judging whether quality of a pulse beam is satisfactory or not, and having a process using the pulse beam in a standby state until the judgment result becomes satisfactory. SOLUTION: In a case where a stepper side is at a timing to access a laser beam source 10 when a signal BEAM RDY is NG (Hi level) during dummy oscillation, a control system 40 on the stepper side monitors the signal BEAM RDY prior to changing a signal STEP.ST. to a Lo level. When the signal BEAM RDY is NG, inversion of the signal STEP.ST. at the Lo level is stopped, and the signal BEAM RDY is continuously monitored. The laser beam source side executes beam quality high-speed return as the signal BEAM RDY is NG, and when the beam quality is returned to the original state, the signal BEAM RDY is set at the Lo level (OK).

Patent
04 Sep 1997
TL;DR: In this article, the detection unit identifies the switch position between two end positions of the closed-loop controlled system by using a servo positioning unit located on a rotatable shaft.
Abstract: The detection unit identifies the switch position between two end positions of the closed-loop controlled system. It is electronically regulated using a servo positioning unit located on a rotatable shaft. It has a required number of optical signal barrier elements (I-V), arranged in pairs close to each other consisting of a transmitter and a sensor (5,6). Also a transparent control wheel (7) is coupled with the movements of the adjusting elements (1) of the regulating section, which on its side away from the light barriers has a number of prism bars (A-E). The prism surfaces respectively extend over one of the signal barrier elements. The beam axis (10) of the optical signal, reflects at an angle the signal beam from the transmitter (5) to the sensor (6). Also for the purpose of forming a coding pattern the prism surfaces are divided in sections of a different length.

Patent
04 Dec 1997
TL;DR: In this article, an optical waveguide with a core 30 and a first cladding 10 surrounding core is configured to amplify a signal beam having a normalised intensity distribution, where the intensity of signal beam is smaller than its peak intensity.
Abstract: Apparatus for amplifying a signal beam having a normalised intensity distribution (Figure 2) comprises, an optical waveguide with a core 30, and a first cladding 10 surrounding core. There is at least one pump beam source configured to supply optical pumping. The gain medium 20 is configured to be pumped by the optical beam, and the gain medium 20 is situated in a region of the optical waveguide where the intensity of signal beam is smaller than its peak intensity. The apparatus is configured to have an effective area ratio of between one and 10. The gain medium 20 may be doped with Ytterbium to produce an amplified wavelength in the range from 950 nm to 1050 nm. The gain medium 20 may be doped with erbium to produce an amplified wavelength in the range from 1450 nm to 1600 nm. The gain medium 20 may be doped with Nd to produce an amplified wavelength in the range 850 nm to 950 nm. The first cladding 10 which may guide the optical pump beam can be surrounded by a second cladding 210 having a lower refractive index in the first cladding.

Journal ArticleDOI
TL;DR: Photorefractive BaTiO(3):Ce was used to combine coherently a signal beam and two amplified pump beams at lambda=678 nm and 40% of the power could be transferred to the signal beam without transferring the phase distortions of the pump beams.
Abstract: Photorefractive BaTiO3:Ce was used to combine coherently a signal beam and two amplified pump beams at λ=678 nm. The master laser beam was split and then amplified in two semiconductor laser amplifiers with gain of as much as 6. The amplifiers were made from quantum-well laser chips by use of antireflection coating. 40% of the power could be transferred to the signal beam without transferring the phase distortions of the pump beams.

Patent
12 Aug 1997
TL;DR: In this paper, the problem of obtaining an optical recording medium having good Bragg selecting performance while using a laminated structure body by using a technique by which the selecting performance is equal to or less than a specified amount even though the medium thickness of a single active area is changed by equal to and more than the specified amount.
Abstract: PROBLEM TO BE SOLVED: To obtain an optical recording medium having good Bragg selecting performance while using a laminated structure body by using a technique by which the selecting performance is equal to or less than a specified amount even though the medium thickness of a single active area is changed by equal to or more than the specified amount. SOLUTION: A function for writing and re-constituting many holograms (that is, equal to or more than L/5λ) depends on a fact that the technique having unchanging selecting performance is adopted. L is defined as the thickness of the single active layer, and λis defined as the wavelength of light to be used. The laminated medium has at least two active areas 3, and the areas 3 are separated by inactive areas 1 and 2. The thickness of the areas 3 versus the thickness of the areas 1 and 2 is <=10:1, and desirably <=5:1. Thus, the writing technique used for performing recording uses the laminated medium having the unchanging performance. The decision must be done in the case thickness of an area where a signal beam and a reference beam are superposed each other is equal to or more than the thickness of the medium.

Journal ArticleDOI
TL;DR: In this article, the phase-matching angle and pump energy dependence of transverse beam profiles on traveling-wave parametric generation in KTiOPO 4 crystals are numerically calculated and compared with the previously measured results.

Patent
20 Oct 1997
TL;DR: In this article, a nonlinear optical waveguide having the dependency to nonlinear phase shift signal optical polarization is used to obtain a sufficiently high quenching ratio, even though the signal light beam polarization is independent to the signal beam polarization by the propagation in the waveguides 1 and 3.
Abstract: PROBLEM TO BE SOLVED: To obtain a sufficiently high quenching ratio even though a nonlinear optical waveguide having the dependency to nonlinear phase shift signal optical polarization is used by constituting a nonlinear refractive index variation expressing section of two nonlinear optical waveguides. SOLUTION: The nonlinear refractive index variation expressing section of the optical switch is constituted of two nonlinear optical waveguides 1 and 3. The signal light beams, which are propagated in a first nonlinear optical waveguide with a TE polarization condition, are propagated in a TE polarization state in a second nonlinear waveguide 3. Conversely, the signal light beams, which are propagated in the waveguide 1 with a TM polarization condition, are propagated in the waveguide 3 in a TE polarization state. In other words, the received nonlinear phase shift of the signal light beams becomes independent to the signal beam polarization by the propagation in the waveguides 1 and 3. Thus, the linearly polarized components, which are mutually orthogonal, receive a π radian nonlinear phase shift, the signal light beams, which are outputted immediately after the completion of a switching operation, completely return to an initial condition and the quenching ratio is improved. COPYRIGHT: (C)1999,JPO