WO2001006606A1 - Generation of stimulated raman scattering laser radiation - Google Patents

Generation of stimulated raman scattering laser radiation Download PDF

Info

Publication number
WO2001006606A1
WO2001006606A1 PCT/BY2000/000004 BY0000004W WO0106606A1 WO 2001006606 A1 WO2001006606 A1 WO 2001006606A1 BY 0000004 W BY0000004 W BY 0000004W WO 0106606 A1 WO0106606 A1 WO 0106606A1
Authority
WO
WIPO (PCT)
Prior art keywords
laser
radiation
active medium
srs
active
Prior art date
Application number
PCT/BY2000/000004
Other languages
French (fr)
Inventor
Alexandr S. Grabtchikov
Alexandr A. Demidovich
Andrei N. Kuzmin
Viktor A. Lisinetsky
Valentin A. Orlovich
Gennady I. Ryabtsev
Original Assignee
Grabtchikov Alexandr S
Demidovich Alexandr A
Kuzmin Andrei N
Lisinetsky Viktor A
Orlovich Valentin A
Ryabtsev Gennady I
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Grabtchikov Alexandr S, Demidovich Alexandr A, Kuzmin Andrei N, Lisinetsky Viktor A, Orlovich Valentin A, Ryabtsev Gennady I filed Critical Grabtchikov Alexandr S
Priority to AU56659/00A priority Critical patent/AU5665900A/en
Priority to EA200200153A priority patent/EA003953B1/en
Publication of WO2001006606A1 publication Critical patent/WO2001006606A1/en

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/106—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity
    • H01S3/108—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity using non-linear optical devices, e.g. exhibiting Brillouin or Raman scattering
    • H01S3/1086—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity using non-linear optical devices, e.g. exhibiting Brillouin or Raman scattering using scattering effects, e.g. Raman or Brillouin effect
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
    • H01S3/16—Solid materials
    • H01S3/163—Solid materials characterised by a crystal matrix
    • H01S3/1675—Solid materials characterised by a crystal matrix titanate, germanate, molybdate, tungstate

Definitions

  • the invention relates to laser engineering, in particular, to the methods of generation of stimulated Raman scattering (SRS) radiation, and can be applied in laser range- finding, communications, ecology, non-linear optics, spectroscopy, etc. to simultaneously produce a set of spectral lines or an individual line in different wavelength ranges, including the eye-safe wavelength range.
  • SRS stimulated Raman scattering
  • SRS is a method widely used to convert the laser frequency to the new spectral ranges.
  • the UV to IR spectrum range can be covered by laser radiation.
  • the problem of increasing the conversion efficiency of the electric power to the optical power in the required spectral interval becomes most topical.
  • An approach based on SRS in the laser resonator cavity is a promising approach in this respect, as it allows direct utilisation of the high intracavity intensity for the SRS- generation.
  • the SRS based on self-conversion is a particular case of SRS. With self- conversion SRS, the laser and SRS generation processes occur in one and the same medium thereby contributing to an increase in the conversion efficiency.
  • the method of SRS generation [J.Findeisen, H.J.Eichler, P.Peuser, Technical Digest of CLEO'99, p. 133 - 1] includes laser generation on the operational transition of the medium in the mode of active quality switching (Q-switching) with further wavelength conversion on SRS in an additionally used non-linear crystal placed within the laser cavity.
  • the active medium is excited with the light of a semiconductor laser.
  • the use of two different active media complicates and increases the cost of the technological process.
  • the method of SRS-generation with self-conversion [ Russian Federation Patent No 21 15983, H 01 S 3/30, Bui. No. 20, 20.07.98 - 2] involves excitation of the active medium, generation of laser radiation at the wavelength of the operational transition of the active medium in the Q-switched resonator and SRS self-conversion of this radiation in the same active medium.
  • the active medium is excited in this case with the light from flash lamps.
  • Such type of pumping is not efficient enough as its energy is distributed across the spectral interval which is considerably broader than the spectral width of the absorption band of the active medium thus causing substantial heat losses and the necessity of the water cooling. The efficiency is 0.17%.
  • microchip-lasers which are characterized by a small length (of about a millimetre) of the active medium [USA Patent 4953166, H01S003/05, H01S000/88, February 9, 1989 - 4].
  • Such lasers contain a pump source and an active medium placed in the cavity formed by an input mirror and output coupler making contact to the active element.
  • a laser may be used as the pump source.
  • the cavity length is selected such that the gain bandwidth of the active element is narrower than the frequency separation between the cavity modes. Such relationship allows generation of only one longitudinal mode whose frequency falls within the laser gain bandwidth.
  • the object of the present invention is to establish the efficient SRS generation with frequency self-conversion.
  • the efficiency of SRS generation with frequency self- conversion implies the ratio of the SRS output power to the power of a pump source.
  • Another object of the present invention is to provide the possibility of generating ultra-short output pulses.
  • the next object of the present invention is to provide the possibility of generating the light both at an individual frequency and at several frequencies of the output simultaneously or with the possibility of tuning them across the frequency range.
  • the following object of the present invention is to increase the conversion efficiency of the electrical energy to that of the SRS output.
  • One more object of the present invention is creation of the efficient compact and cost- effective devices for the embodiment of the claimed invention.
  • Another object of the present invention is the embodiment of the claimed method in a microchip laser.
  • the first of the foregoing objects on generation of SRS radiation including excitation of an active medium, generation of the laser radiation at the operational transition of the active medium and conversion of this radiation to that of the SRS components in the same active medium is being realized by exciting the active medium with the laser light.
  • the laser radiation on the operational transition of the active medium (“intermediate” laser radiation) is being generated either in the continuous-wave (CW) or in the Q- switched mode.
  • the second object in the claimed method is realized by generating the «intermediate» laser radiation in the mode locking mode in the form of ultra-short output pulses.
  • the next from the foregoing objects is being realized by generating the «intermediate» laser radiation across a wide spectral range.
  • the «intermediate» laser radiation can be generated simultaneously at more than one frequency and the above laser radiation of frequencies with the intensities higher than Raman threshold can be simultaneously converted to the SRS components.
  • Both pulsed and CW radiation can be used to excite the active medium.
  • This can be a highly-diverging beam, such as, for instance the beam from a laser diode.
  • the spectrum of this radiation is selected within the absorption band of the active medium.
  • the pump power is chosen to be 1 W or less
  • the «intermediate» laser radiation is generated at 1.35+0.01 ⁇ m to be further converted to the first 1.54 ⁇ 0.01 ⁇ m- SRS component.
  • the fourth from the foregoing objects is realized by using for pump a laser diode having a high conversion efficiency of the electrical to optical energy.
  • the laser with SRS conversion consisting of a pump source and a resonator cavity, formed by an input mirror and output coupler, and using the cavity active element made of the material converting the radiation generated at it's operational transition to the SRS components, becomes efficient due to that a laser is used for a pump source.
  • a crystal can be used for the active element of such laser.
  • the said laser can contain a Q-switch unit.
  • the pump laser can generate a highly-diverging light and be for instance a laser diode.
  • the claimed laser is additionally equipped with a focusing optical system located between the pump laser and the active element.
  • the input mirror can be made plane and be disposed directly on the input end of the active element, the output coupler can be either spherical or plane, and the Q-switch unit can be positioned between the output end of the active element and the output coupler.
  • the Q-switch unit can be made either as an active or as a passive device. It is advisable that the input mirror is to be made with a maximum transmission at the excitation wavelength, the output end of the active element is made anti-reflective at the ((intermediate)) laser radiation wavelengths and at the wavelengths of the selected SRS component output, the output coupler is made to have a maximum reflectance at the ((intermediate)) laser radiation wavelength medium and the optimal reflectance at the chosen SRS component
  • the Q- switch unit (if required) can be made to have an optimum initial transmission at the ((intermediate)) laser radiation wavelength
  • the input mirror is made with a transmission of 95 ⁇ 0 5% at 0 81 ⁇ 0 01 ⁇ m
  • the active element output end is made anti-reflective at 1 06 ⁇ 0 01 ⁇ m and 1 18 ⁇ 0 01 ⁇ m, while the output coupler is made spherical with a radius of curvature of 50 mm and reflectivity of 99 9 ⁇ 0 05% and 99 5 ⁇ 0 05% at 1 06 ⁇ 0 01 ⁇ m and 1 18 ⁇ 0 01 ⁇ m, respectively
  • the Q-switch unit is fabricated from a YAG Cr 4 " crystal with an initial transmittance of 90+0 5% at 1 06 ⁇ 0 01 ⁇ m
  • the input mirror is made with a transmission of 95+0 5% at 0 8110 01 ⁇ m
  • the active element output end is made anti-reflective at 1 0610 01 ⁇ m, 1 3510 01 ⁇ m and 1 5410 01 ⁇ m, while the output coupler is made spherical with a radius of curvature of 50 mm and reflectivity 99 810 05% at 1 3510 01 ⁇ m and 1 5410 01 ⁇ m, respectively
  • the Q-switch unit is fabricated from a YAG V 3" crystal with an initial transmittance of 9610 5% at 1 3510 01 ⁇ m
  • the laser active element is fabricated to be broad-band, while the components that form the laser cavity are made to be selective restricting the laser action spectral region to a narrow wavelength range with the said selectivity being made variable
  • the laser a microchip laser, that contains a pump source and a cavity formed by an input mirror and output coupler with an active element in between
  • the active element is made from a material converting the laser radiation wavelength generated on it's operational transition (((intermediate)) laser radiation) to the SRS components.
  • a laser can be used for a pump source.
  • the formulated object can be realized due to the feasibility of using the laser exciting beams with different divergence, including that considerably exceeding the diffraction divergence
  • the generated laser radiation fills the entire resonator cavity, including the complete length of the active medium, thus also allowing SRS generation across the entire length of the active medium.
  • the generated intracavity "intermediate" power can be considerably higher than the input power as a result of accumulation of radiation energy in the resonator what also contributes to the SRS process.
  • the possibility is provided for the efficient conversion of the low-quality laser light (highly-diverging) to the ((intermediate)) laser radiation with a good beam quality (slightly-diverging) with its further efficient SRS conversion.
  • Fig.1 schematically presents the laser action using as an example one of the embodiments of the claimed device.
  • Fig.2 schematically presents another embodiment of the claimed device
  • Fig 3 schematically presents the microchip laser.
  • Fig. 4 gives the spectrum of the generated light.
  • Fig. 5 presents the dependencies of the "intermediate” laser radiation power and the SRS Stokes component power on the pump power.
  • Fig. 6 gives the spectrum of the generated light in the other embodiment of the claimed device.
  • Fig 7 shows the laser output spectrum for a broad frequency range.
  • Fig.8 presents the dependencies of the "intermediate” laser radiation power and the SRS Stokes component power on the pump power in the other embodiment of the claimed device.
  • the claimed device contains a pump laser 1, an optic system 2 and an active medium in the shape of a crystal active element 3, placed in the cavity formed by mirrors 4 and 5
  • the input mirror 4 is fabricated plane and is disposed directly on the input end of the crystal active element 3, the other mirror - output coupler 5 is made semi-spherical while the Q-switch unit is made as an saturable absorber 6 which is disposed between the output end of the crystal active element 3 and output coupler 5
  • the claimed method is realized in the following way.
  • the light of the pump laser 1 is focussed by the optic system 2 into the active element 3 placed in the cavity formed by the mirrors 4 and 5. It is advisable that the input mirror 4 is made to be highly- transmissive at the pump wavelength
  • the output end of the active element 3 is made to be anti-reflective at the ((intermediate)) laser radiation wavelengths and at the wavelengths of the selected SRS component
  • the output coupler 5 is made highly-reflective at the ((intermediate)) laser radiation wavelength and optimally- reflective at the wavelength of the selected SRS component.
  • the claimed method is being realized in the Q-switched mode and the saturable absorber 6 is made to have an optimum initial transmittance at the ((intermediate)) laser radiation wavelength
  • the ((intermediate)) laser radiation is converted by SRS in the same medium 3 to a set of SRS components (Stokes and anti-Stokes) which emit through the mirror 5 being partially reflective at these wavelengths.
  • the output spectrum is measured with the monochromator 7 connected to the CCD array 8, the output power is measured with the power meter 9, the pulse repetition rate and the pulse shape is measured with a photodetector and the oscilloscope 10.
  • Individual output wavelengths are separated by the spectral filters 1 1.
  • the output radiation is divided to several rays by means of the mirrors 12 o
  • Fig.4 illustrates the presence of Stokes and anti-Stokes SRS components in the output.
  • the selective elements ensure the "intermediate" laser generation at several wavelengths, the simultaneous radiation at these wavelengths in the same crystal will be converted to the corresponding SRS output.
  • the broad gain bandwidth also allows realization of the mode-locked laser operation mode to produce ultra-short (pico-femtosecond) pulses.
  • Mode locking is a completely ordered laser operation mode that can be realized when a set of longitudinal modes ensure definite phase and amplitude relationships between the modes.
  • the output radiation will be a regular time function, i.e. a regular train of mode-locked laser pulses.
  • a train of laser pulses is converted with SRS in the same active medium into a train of SRS pulses.
  • the laser in the microchip embodiment (Fig.3) [See IJ.Zayhowski, J.Harrison “Miniature Solid-state Lasers” - 6] contains the pump source 1, the optic system 2 and the resonant cavity formed by the input mirror 4 and the output couple 5 with the active element 3 in between.
  • the active element 3 is made of a material converting the ((intermediate)) laser radiation to the SRS components.
  • a laser can be used for the pump source 1.
  • the Q-switch unit 6 is used.
  • the input mirror 4 is disposed in a close vicinity to the active element 3. It can be directly applied on its input end.
  • the Q-switch unit 6, with the output coupler 5 applied on its output end, is disposed in a close vicinity to the output end of the active element 3
  • the laser cavity length is selected such that the transmission bandwidth of the active element is smaller than the frequency separation between the cavity modes Such relationship allows generation of only one longitudinal mode whose frequency falls within the laser gain bandwidth The eneigy of the mode of the generated light turns out to be high enough foi the SRS conversion to occur in one crystal
  • the laser radiation is generated in the active element by the input beam having a wavelength falling within the absorption band of the active medium This reduces the heat losses and increases the conversion efficiency of the pump power to the output power The decrease in heat losses allows one to refuse from water-cooling
  • the claimed method and the device are realized according to a particular schematic that employs a KGW Nd 1 ' 4 m -dia and 10 mm . long ⁇ crystal cut- along the b crystallographic axis and excited with a 1 W- highly-diverging highly-astigmatic ( 12x40 degie b) ⁇ utpul beam of a P ⁇ laioid POL-4100 laser diode at 0 81 ⁇ m
  • the "intermediate" lasei idiation is generated at 1 067 ⁇ m to be further converted to the Stokes ( 1 181 ⁇ m) and anti-Stokes (0 973 ⁇ m) components
  • the optic system consists of a col mator with an aperture of 0 5, two astigmatism-compensating 4 5 X cylindrical lens, and a spherical lens with a focal length of 10 mm and focuses the pump beam to the circular spot with the diameter of about 100 ⁇ m
  • the resonator is formed by a plane and a spherical mirror
  • the plane mirror was applied to the crystal end and has a transmission of 95% at 0 81 ⁇ m and reflectivity of 99 9% and 99 5% at 1 067 ⁇ m and 1 181 ⁇ m, respectively
  • the other end is anti- reflection coated at 1 067 ⁇ m and 1 181 ⁇ m
  • the spherical mirror has a curvature radius of 50 mm and reflectivities of 99.9% and 99 5% at 1.067 ⁇ m and 1.181 ⁇ m, respectively
  • the Q-switch unit is made from YAG.Cr 4+ and has an initial transmission of 90% at 1 067 ⁇ m
  • the Stokes generation threshold in this embodiment coincides with the laser generation threshold and is not more than 12 MW/cm 2 .
  • the claimed method allows the SRS generation threshold to be an order - of magnitude decreased and the conversion efficiency to be eight times increased compared to [2], a further increase in the conversion efficiency is also K) feasible through the optimisation of the cavity parameters.
  • Another embodiment of the claimed method employs an active medium from a KGW:Nd 3+ 4 mm-dia. and 10 mm long crystal, cut along the b crystallographic axis excited with a 2 W-highly-di verging highly-astigmatic beam from a laser diode at 15 0.81 ⁇ m.
  • the ((intermediate)) laser radiation is generated at 1.351 ⁇ m with the subsequent conversion to the Stokes (1.538 ⁇ m) component.
  • the optic system consists of a collimator with an aperture of 0.5, two astigmatism-compensating 4.5 X cylindrical lenses, and a spherical lens with a focal length of 10 mm and focuses the pump beam to the circular spot with the diameter of about 150 ⁇ m. 0
  • the cavity is formed by a plane and spherical mirrors.
  • the plane mirror is applied to the crystal end and had a transmission of 90% at 0.81 ⁇ m and reflectivity of 99.9% and 99.85% at 1.351 ⁇ m and 1.538 ⁇ m, respectively.
  • the other end is anti-reflection coated at 1.067 ⁇ m, 1.351 ⁇ m and 1.538 ⁇ m.
  • the spherical mirror has a radius of 5 curvature of 50 mm and reflectivity of 99.9% and 99.85% at 1.351 ⁇ m and 1.538 ⁇ m, respectively.
  • the Q-switch unit is fabricated from a YAG:V 3+ crystal and has an initial transmission of 96% at 1.351 ⁇ m.
  • the spectrums of the generated ((intermediate)) laser radiation and Stokes radiation for this example are given at Fig. 6
  • the next embodiment of the claimed method employs an active medium from a KYW:Yb 3* crystal of 4x4x0.8 mm size, cut along the b crystallographic axis and excited with a 1 W-highly-diverging light from a laser diode at 0.98 ⁇ m.
  • the optic system consists of a collimating mirror with an aperture of 0.5, two astigmatism- compensating 4.5 N cylindrical lenses, and a spherical lens with a focal length of 10 mm and focuses the pump beam to the circular spot with the diameter of about 100 ⁇ m
  • the cavity is formed by a plane and spherical mirrors
  • the active crystal is applied to the plane mirror being anti-reflection coated at 980 ⁇ m and being highly-reflective at the ((intermediate)) laser radiation wavelengths and the wavelengths of the corresponding Stokes components Both ends of the crystal are anti-reflection coated at the ((intermediate)) laser radiation wavelengths
  • the spherical mirror has a curvature radius of 50 mm and a reflectivity varying from 99 45 to 99 7% at the ((intermediate)) laser radiation wavelengths and that of 99 9% at the wavelengths of the corresponding Stokes components
  • the Q-switch unit is fabricated from YAG Cr 4" and has an initial transmission of 97% at 1030 ⁇ m
  • the wavelength of the ((intermediate)) laser radiation can be tuned in wide spectrum range thus causing the tuning of the wavelength of the corresponding Stokes component.
  • Fig 7 demonstrates the possibility of tuning of the Stokes component wavelength in the spectrum range 1 136 ⁇ m -1 1385 ⁇ m by means of tuning of the ((intermediate)) laser radiation wavelength
  • the efficient SRS conversion is obtained using a highly- diverging beam of a multi-mode semiconductor laser to pump the active medium
  • the decrease in the divergence of the pump beam in the claimed method does not affect the conditions of the SRS dynamics (the confocal length of the pump beam increases up to the dimensions of the active medium)
  • the claimed method will be also efficient with smaller divergences

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Nonlinear Science (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Optics & Photonics (AREA)
  • Lasers (AREA)
  • Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)

Abstract

The invention relates to laser engineering, in particular, to the methods of generation of stimulated Raman scattering (SRS) radiation, and can be applied in laser range-finding, communications, ecology, non-linear optics, spectroscopy, etc., to simultaneously produce a set of spectral lines or an individual line in different wavelength ranges, including the eye-safe wavelength range. The efficient generation of SRS radiation including excitation of an active medium, generation of the laser radiation at the operational transition of the active medium and conversion of this radiation to that of the SRS components in the same active medium is being realized by exciting the active medium with the laser light.

Description

Generation of Stimulated Raman Scattering Laser Radiation
Field of Invention
The invention relates to laser engineering, in particular, to the methods of generation of stimulated Raman scattering (SRS) radiation, and can be applied in laser range- finding, communications, ecology, non-linear optics, spectroscopy, etc. to simultaneously produce a set of spectral lines or an individual line in different wavelength ranges, including the eye-safe wavelength range.
Prior Art
SRS is a method widely used to convert the laser frequency to the new spectral ranges. At present, with SRS generation, the UV to IR spectrum range can be covered by laser radiation. The problem of increasing the conversion efficiency of the electric power to the optical power in the required spectral interval becomes most topical. An approach based on SRS in the laser resonator cavity is a promising approach in this respect, as it allows direct utilisation of the high intracavity intensity for the SRS- generation. The SRS based on self-conversion is a particular case of SRS. With self- conversion SRS, the laser and SRS generation processes occur in one and the same medium thereby contributing to an increase in the conversion efficiency.
The method of SRS generation [J.Findeisen, H.J.Eichler, P.Peuser, Technical Digest of CLEO'99, p. 133 - 1] includes laser generation on the operational transition of the medium in the mode of active quality switching (Q-switching) with further wavelength conversion on SRS in an additionally used non-linear crystal placed within the laser cavity. The active medium is excited with the light of a semiconductor laser. The use of two different active media complicates and increases the cost of the technological process.
The method of SRS-generation with self-conversion [Russian Federation Patent No 21 15983, H 01 S 3/30, Bui. No. 20, 20.07.98 - 2] involves excitation of the active medium, generation of laser radiation at the wavelength of the operational transition of the active medium in the Q-switched resonator and SRS self-conversion of this radiation in the same active medium. The active medium is excited in this case with the light from flash lamps. Such type of pumping, however, is not efficient enough as its energy is distributed across the spectral interval which is considerably broader than the spectral width of the absorption band of the active medium thus causing substantial heat losses and the necessity of the water cooling. The efficiency is 0.17%.
Generation of coherent radiation with a tunable wavelength using the non-linear optical conversion of the laser tunable radiation, in particular, based on SRS is known [V.Demtreder. Laser spectroscopy. M. Nauka, 1985, p.279 - 3].
So called microchip-lasers are known which are characterized by a small length (of about a millimetre) of the active medium [USA Patent 4953166, H01S003/05, H01S000/88, February 9, 1989 - 4]. Such lasers contain a pump source and an active medium placed in the cavity formed by an input mirror and output coupler making contact to the active element. A laser may be used as the pump source. The cavity length is selected such that the gain bandwidth of the active element is narrower than the frequency separation between the cavity modes. Such relationship allows generation of only one longitudinal mode whose frequency falls within the laser gain bandwidth.
Summary of the Invention
The object of the present invention is to establish the efficient SRS generation with frequency self-conversion. The efficiency of SRS generation with frequency self- conversion implies the ratio of the SRS output power to the power of a pump source.
Another object of the present invention is to provide the possibility of generating ultra-short output pulses.
The next object of the present invention is to provide the possibility of generating the light both at an individual frequency and at several frequencies of the output simultaneously or with the possibility of tuning them across the frequency range. The following object of the present invention is to increase the conversion efficiency of the electrical energy to that of the SRS output.
One more object of the present invention is creation of the efficient compact and cost- effective devices for the embodiment of the claimed invention.
Another object of the present invention is the embodiment of the claimed method in a microchip laser.
The first of the foregoing objects on generation of SRS radiation including excitation of an active medium, generation of the laser radiation at the operational transition of the active medium and conversion of this radiation to that of the SRS components in the same active medium is being realized by exciting the active medium with the laser light.
The laser radiation on the operational transition of the active medium ("intermediate" laser radiation) is being generated either in the continuous-wave (CW) or in the Q- switched mode.
The second object in the claimed method is realized by generating the «intermediate» laser radiation in the mode locking mode in the form of ultra-short output pulses.
The next from the foregoing objects is being realized by generating the «intermediate» laser radiation across a wide spectral range. By continuously varying the frequency of the laser light over the specified spectral range, the light is being converted to the SRS components with their frequencies being correspondingly changed. Besides, the «intermediate» laser radiation can be generated simultaneously at more than one frequency and the above laser radiation of frequencies with the intensities higher than Raman threshold can be simultaneously converted to the SRS components.
Both pulsed and CW radiation can be used to excite the active medium. This can be a highly-diverging beam, such as, for instance the beam from a laser diode. The spectrum of this radiation is selected within the absorption band of the active medium. In one of the embodiment of the claimed method, the pump power is chosen to be 1 W or less, the «intermediate» laser radiation at 1.06+0.01 μm to be further converted to the SRS components, with the first 1.18+0.01 μm, second 1.32±0.01 μm- and third 1.50±0.01 μm- SRS component or a group of SRS components consisting of, at least one Stokes- and one anti-Stokes component, being separated.
In another embodiment of the claimed method, the «intermediate» laser radiation is generated at 1.35+0.01 μm to be further converted to the first 1.54±0.01 μm- SRS component.
The fourth from the foregoing objects is realized by using for pump a laser diode having a high conversion efficiency of the electrical to optical energy.
The laser with SRS conversion consisting of a pump source and a resonator cavity, formed by an input mirror and output coupler, and using the cavity active element made of the material converting the radiation generated at it's operational transition to the SRS components, becomes efficient due to that a laser is used for a pump source.
A crystal can be used for the active element of such laser.
Besides, the said laser can contain a Q-switch unit.
The pump laser can generate a highly-diverging light and be for instance a laser diode.
The claimed laser is additionally equipped with a focusing optical system located between the pump laser and the active element. The input mirror can be made plane and be disposed directly on the input end of the active element, the output coupler can be either spherical or plane, and the Q-switch unit can be positioned between the output end of the active element and the output coupler.
The Q-switch unit can be made either as an active or as a passive device. It is advisable that the input mirror is to be made with a maximum transmission at the excitation wavelength, the output end of the active element is made anti-reflective at the ((intermediate)) laser radiation wavelengths and at the wavelengths of the selected SRS component output, the output coupler is made to have a maximum reflectance at the ((intermediate)) laser radiation wavelength medium and the optimal reflectance at the chosen SRS component The Q- switch unit (if required) can be made to have an optimum initial transmission at the ((intermediate)) laser radiation wavelength
In one of the embodiment of the claimed laser the input mirror is made with a transmission of 95±0 5% at 0 81±0 01 μm The active element output end is made anti-reflective at 1 06±0 01 μm and 1 18±0 01 μm, while the output coupler is made spherical with a radius of curvature of 50 mm and reflectivity of 99 9±0 05% and 99 5±0 05% at 1 06±0 01 μm and 1 18±0 01 μm, respectively The Q-switch unit is fabricated from a YAG Cr4" crystal with an initial transmittance of 90+0 5% at 1 06±0 01 μm
In the other embodiment of the claimed laser the input mirror is made with a transmission of 95+0 5% at 0 8110 01 μm The active element output end is made anti-reflective at 1 0610 01 μm, 1 3510 01 μm and 1 5410 01 μm, while the output coupler is made spherical with a radius of curvature of 50 mm and reflectivity 99 810 05% at 1 3510 01 μm and 1 5410 01 μm, respectively The Q-switch unit is fabricated from a YAG V3" crystal with an initial transmittance of 9610 5% at 1 3510 01 μm
To realize the second of the foregoing objects, the laser active element is fabricated to be broad-band, while the components that form the laser cavity are made to be selective restricting the laser action spectral region to a narrow wavelength range with the said selectivity being made variable
The last of the foregoing objects is realized in the second variant of the laser - a microchip laser, that contains a pump source and a cavity formed by an input mirror and output coupler with an active element in between This object is realised due to that the active element is made from a material converting the laser radiation wavelength generated on it's operational transition (((intermediate)) laser radiation) to the SRS components. A laser can be used for a pump source.
The formulated object can be realized due to the feasibility of using the laser exciting beams with different divergence, including that considerably exceeding the diffraction divergence The use of laser beams with different divergences for pump characterized by that with increasing beam divergence, the length of the waist, where the output power density is a maximum, decreases. In the present embodiment, no matter whether lasing occurs in the part of the active element (when a highly-diverging pump beam is used) or across the entire active medium (when a low-diverging pump beam is used), the generated laser radiation fills the entire resonator cavity, including the complete length of the active medium, thus also allowing SRS generation across the entire length of the active medium. Besides, the generated intracavity "intermediate" power can be considerably higher than the input power as a result of accumulation of radiation energy in the resonator what also contributes to the SRS process.
Thus, the possibility is provided for the efficient conversion of the low-quality laser light (highly-diverging) to the ((intermediate)) laser radiation with a good beam quality (slightly-diverging) with its further efficient SRS conversion.
Brief Description of the Drawings
Fig.1 schematically presents the laser action using as an example one of the embodiments of the claimed device. Fig.2 schematically presents another embodiment of the claimed device Fig 3 schematically presents the microchip laser. Fig. 4 gives the spectrum of the generated light. Fig. 5 presents the dependencies of the "intermediate" laser radiation power and the SRS Stokes component power on the pump power. Fig. 6 gives the spectrum of the generated light in the other embodiment of the claimed device. Fig 7 shows the laser output spectrum for a broad frequency range. Fig.8 presents the dependencies of the "intermediate" laser radiation power and the SRS Stokes component power on the pump power in the other embodiment of the claimed device. Detailed Description of the Inventions
The claimed method is described using as an example one of the embodiments of the device from Fig 1
The claimed device contains a pump laser 1, an optic system 2 and an active medium in the shape of a crystal active element 3, placed in the cavity formed by mirrors 4 and 5 The input mirror 4 is fabricated plane and is disposed directly on the input end of the crystal active element 3, the other mirror - output coupler 5 is made semi-spherical while the Q-switch unit is made as an saturable absorber 6 which is disposed between the output end of the crystal active element 3 and output coupler 5
In another embodiment (Fig.2) of the present invention the output coupler 5 is made plane
The claimed method is realized in the following way. The light of the pump laser 1 is focussed by the optic system 2 into the active element 3 placed in the cavity formed by the mirrors 4 and 5. It is advisable that the input mirror 4 is made to be highly- transmissive at the pump wavelength The output end of the active element 3 is made to be anti-reflective at the ((intermediate)) laser radiation wavelengths and at the wavelengths of the selected SRS component And the output coupler 5 is made highly-reflective at the ((intermediate)) laser radiation wavelength and optimally- reflective at the wavelength of the selected SRS component. In this case the claimed method is being realized in the Q-switched mode and the saturable absorber 6 is made to have an optimum initial transmittance at the ((intermediate)) laser radiation wavelength The ((intermediate)) laser radiation is converted by SRS in the same medium 3 to a set of SRS components (Stokes and anti-Stokes) which emit through the mirror 5 being partially reflective at these wavelengths. The output spectrum is measured with the monochromator 7 connected to the CCD array 8, the output power is measured with the power meter 9, the pulse repetition rate and the pulse shape is measured with a photodetector and the oscilloscope 10. Individual output wavelengths are separated by the spectral filters 1 1. The output radiation is divided to several rays by means of the mirrors 12 o
The spectrum from Fig.4 illustrates the presence of Stokes and anti-Stokes SRS components in the output.
There can be presented another embodiment of the claimed method, which employs laser active element with a broad gain bandwidth. The components, forming the laser cavity, cause in this case selective losses limiting the ((intermediate)) laser radiation wavelength by a narrow spectral interval and the said laser wavelength can be continuously tunable within the gain bandwidth by adjusting the selective losses. The wavelengths of the simultaneously generated Stokes components will be also continuously tuned.
If the selective elements ensure the "intermediate" laser generation at several wavelengths, the simultaneous radiation at these wavelengths in the same crystal will be converted to the corresponding SRS output.
In addition to the feasibility of generating the tunable radiation, the broad gain bandwidth also allows realization of the mode-locked laser operation mode to produce ultra-short (pico-femtosecond) pulses.
Mode locking [see "Ultra-short light pulses" edited by S.Shapiro. M. Mir, 1981, p.38 - 5] is a completely ordered laser operation mode that can be realized when a set of longitudinal modes ensure definite phase and amplitude relationships between the modes. In this case the output radiation will be a regular time function, i.e. a regular train of mode-locked laser pulses. In our case a train of laser pulses is converted with SRS in the same active medium into a train of SRS pulses.
The laser in the microchip embodiment (Fig.3) [See IJ.Zayhowski, J.Harrison "Miniature Solid-state Lasers" - 6] contains the pump source 1, the optic system 2 and the resonant cavity formed by the input mirror 4 and the output couple 5 with the active element 3 in between. The active element 3 is made of a material converting the ((intermediate)) laser radiation to the SRS components. A laser can be used for the pump source 1. In this embodiment the Q-switch unit 6 is used. The input mirror 4 is disposed in a close vicinity to the active element 3. It can be directly applied on its input end. The Q-switch unit 6, with the output coupler 5 applied on its output end, is disposed in a close vicinity to the output end of the active element 3 The laser cavity length is selected such that the transmission bandwidth of the active element is smaller than the frequency separation between the cavity modes Such relationship allows generation of only one longitudinal mode whose frequency falls within the laser gain bandwidth The eneigy of the mode of the generated light turns out to be high enough foi the SRS conversion to occur in one crystal
In any embodiment of the claimed method and in any embodiment of the claimed device, the laser radiation is generated in the active element by the input beam having a wavelength falling within the absorption band of the active medium This reduces the heat losses and increases the conversion efficiency of the pump power to the output power The decrease in heat losses allows one to refuse from water-cooling
Preferable Embodiments of the Invention
The claimed method and the device are realized according to a particular schematic that employs a KGW Nd1' 4 m -dia and 10 mm . long ^crystal cut- along the b crystallographic axis and excited with a 1 W- highly-diverging highly-astigmatic ( 12x40 degie b) υutpul beam of a Pυlaioid POL-4100 laser diode at 0 81 μm The "intermediate" lasei idiation is generated at 1 067 μm to be further converted to the Stokes ( 1 181 μm) and anti-Stokes (0 973 μm) components The optic system consists of a col mator with an aperture of 0 5, two astigmatism-compensating 4 5X cylindrical lens, and a spherical lens with a focal length of 10 mm and focuses the pump beam to the circular spot with the diameter of about 100 μm
The resonator is formed by a plane and a spherical mirror The plane mirror was applied to the crystal end and has a transmission of 95% at 0 81 μm and reflectivity of 99 9% and 99 5% at 1 067 μm and 1 181 μm, respectively The other end is anti- reflection coated at 1 067 μm and 1 181 μm The spherical mirror has a curvature radius of 50 mm and reflectivities of 99.9% and 99 5% at 1.067 μm and 1.181 μm, respectively The Q-switch unit is made from YAG.Cr4+ and has an initial transmission of 90% at 1 067 μm The Stokes generation threshold in this embodiment coincides with the laser generation threshold and is not more than 12 MW/cm2.
From the dependence in Fig.5 it is evident that the maximum achievable average 5 power of the Stokes radiation is 8.9 mW what makes 1.3% of the input power.
Thus in this embodiment the claimed method allows the SRS generation threshold to be an order - of magnitude decreased and the conversion efficiency to be eight times increased compared to [2], a further increase in the conversion efficiency is also K) feasible through the optimisation of the cavity parameters.
Another embodiment of the claimed method employs an active medium from a KGW:Nd3+ 4 mm-dia. and 10 mm long crystal, cut along the b crystallographic axis excited with a 2 W-highly-di verging highly-astigmatic beam from a laser diode at 15 0.81 μm. The ((intermediate)) laser radiation is generated at 1.351 μm with the subsequent conversion to the Stokes (1.538 μm) component. The optic system consists of a collimator with an aperture of 0.5, two astigmatism-compensating 4.5X cylindrical lenses, and a spherical lens with a focal length of 10 mm and focuses the pump beam to the circular spot with the diameter of about 150 μm. 0
The cavity is formed by a plane and spherical mirrors. The plane mirror is applied to the crystal end and had a transmission of 90% at 0.81 μm and reflectivity of 99.9% and 99.85% at 1.351 μm and 1.538 μm, respectively. The other end is anti-reflection coated at 1.067 μm, 1.351 μm and 1.538 μm. The spherical mirror has a radius of 5 curvature of 50 mm and reflectivity of 99.9% and 99.85% at 1.351 μm and 1.538 μm, respectively. The Q-switch unit is fabricated from a YAG:V3+ crystal and has an initial transmission of 96% at 1.351 μm. The spectrums of the generated ((intermediate)) laser radiation and Stokes radiation for this example are given at Fig. 6
o The next embodiment of the claimed method employs an active medium from a KYW:Yb3* crystal of 4x4x0.8 mm size, cut along the b crystallographic axis and excited with a 1 W-highly-diverging light from a laser diode at 0.98 μm. The optic system consists of a collimating mirror with an aperture of 0.5, two astigmatism- compensating 4.5N cylindrical lenses, and a spherical lens with a focal length of 10 mm and focuses the pump beam to the circular spot with the diameter of about 100 μm
The cavity is formed by a plane and spherical mirrors The active crystal is applied to the plane mirror being anti-reflection coated at 980 μm and being highly-reflective at the ((intermediate)) laser radiation wavelengths and the wavelengths of the corresponding Stokes components Both ends of the crystal are anti-reflection coated at the ((intermediate)) laser radiation wavelengths
The spherical mirror has a curvature radius of 50 mm and a reflectivity varying from 99 45 to 99 7% at the ((intermediate)) laser radiation wavelengths and that of 99 9% at the wavelengths of the corresponding Stokes components The Q-switch unit is fabricated from YAG Cr4" and has an initial transmission of 97% at 1030 μm
The wavelength of the ((intermediate)) laser radiation can be tuned in wide spectrum range thus causing the tuning of the wavelength of the corresponding Stokes component. Fig 7 demonstrates the possibility of tuning of the Stokes component wavelength in the spectrum range 1 136 μm -1 1385 μm by means of tuning of the ((intermediate)) laser radiation wavelength
On the Fig 8 the dependencies of the "intermediate" laser radiation power and SRS Stokes component output powers on the pump power are presented It is shown that the maximum Stokes radiation power is 14 5 mW
Thus, in stated embodiments, the efficient SRS conversion is obtained using a highly- diverging beam of a multi-mode semiconductor laser to pump the active medium As the decrease in the divergence of the pump beam in the claimed method does not affect the conditions of the SRS dynamics (the confocal length of the pump beam increases up to the dimensions of the active medium), a conclusion can be made that the claimed method will be also efficient with smaller divergences
The scope of the claimed invention is not limited by the given examples

Claims

Claims
1. A method of generating the laser radiation based on stimulated Raman scattering (SRS) comprising excitation of an active medium, generation of laser radiation on the operational transition of the active medium and conversion of this radiation to that of SRS components in the same active medium, wherein the active medium is excited by the laser light.
2. A method according to claim 1, wherein the generation of laser radiation at the operational transition of the active medium is effected in the continuous-wave mode.
3 A method according to claim 1, wherein the generation of laser radiation at the operational transition of the active medium is effected in the Q-switched mode
4. A method according to claim 1, wherein the generation of the laser radiation on the operational transition of the active medium is effected in the mode-locked mode in the form of ultra-short pulses
5 A method according to claim 1 , wherein the generation of laser radiation at the operational transition of the active medium is effected over a broad frequency range
6 A method according to claim 5, wherein by varying the frequency of the said laser radiation in the specified frequency range, the radiation is simultaneously converted to SRS components with their frequencies being continuously tuned
7. A method according to claim 5, wherein the generation of laser radiation at the operational transition of the active medium is carried out at more than one frequency simultaneously.
8 A method according to claim 7, wherein said laser radiation frequencies with the intensities higher than Raman threshold are converted to SRS components simultaneously
A method according to claim 1, wherein the light used for excitation of the active medium is a pulsed radiation
A method according to claim 1, wherein the light used for excitation of the active medium is a continuous-wave radiation
A method according to any of claims 1, 9 or 10, wherein the active medium is excited with a highly-diverging beam
A method according to claim 1 1 , wherein the active medium is excited with the diode laser radiation
A method according to any of claims 1 - 12, wherein the spectrum of the radiation used to excite the active medium is selected within the absorption band of the active medium
A method according to any of claims 1-13 , wherein the active medium is excited with an input power of 1 W or less
A method according to claim 3, wherein the laser radiation is generated on the operational transition of the active medium at 1 0610 01 μm
A method according to claim 15, wherein the laser radiation generated on the operational transition of the active medium is converted to the first 1 1810 01 μm -Stokes component
A method according to claim 16, wherein the first 1 1810 01 μm -Stokes component is converted to the second 1 3210 01 μm -Stokes component
A method according to claim 17, wherein is converted to the second 1 3210 Olμm -Stokes component is converted to the third 1 5010 01 μm -Stokes component
A method according to claim 3 wherein the laser radiation generation on the operational transition of the active medium is effected at 1 3510 01 μm
A method according to claim 19, wherein the laser radiation generated on the operational transition of the active medium is converted to the first 1 5410 01 μm -Stokes component
21. The method of claim 1, wherein the laser radiation generated on the operational transition of the active medium is converted to a set of SRS components consisting of at least the first Stokes and anti-Stokes components.
22. A laser with conversion of the SRS radiation wavelength comprising a pump source and a cavity formed by an input mirror and output coupler, between which an active element made of a material converting the radiation generated at it's operational transition to the SRS components is disposed, wherein the pump source is a laser.
23. A laser according to claim 22, wherein the active element is made of a crystal.
24. A laser according to claim 22, wherein it additionally comprises a Q-switch unit.
25. A laser according to claim 22, wherein the pump laser is made to produce a highly-diverging beam.
26. A laser according to claim 25, wherein the pump laser is a diode laser.
27. A laser according to claims 25 or 26, wherein it additionally comprises a focusing optical system disposed between the pump laser and the active element.
28. A laser according to claim 22, wherein the input mirror is flat and is disposed directly on the input end of the active element.
29. A laser according to claim 22, wherein the output coupler is spherical.
30. A laser according to claim 22, wherein the output coupler is flat.
3 1. A laser according to any of claims 22 - 30, wherein the Q-switch unit is disposed between the output end of the active element and the output coupler.
32. A laser according to any of claims 22 - 3 1 , wherein the input mirror is made to have a maximum transmission at the pump wavelength. A laser according to claim 32, wherein the said input mirror is made to have a transmittance of 9510.5% at 0 8110 01 μm.
A laser according to any of claims 22 - 33, wherein the output end of the active element is made anti-reflective at the wavelengths of the laser radiation generated on the operational transition of the active element and at the wavelength of the selected SRS component
A laser according to claim 34, wherein the output end of the said active element is made anti-reflective at 1 067 μm and 1.1810.01 μm.
A laser according to claim 34, wherein the output end of the said active element is made anti-reflective at 1 0610 01 μm, 1.3510.01 μm and 1.5410.01 μm
A laser according to any of claims 22 - 36, wherein the output coupler is made to have a maximum reflectance at the wavelength of the laser radiation generated on the operational transition of the active element and an optimum reflectance at the wavelength of the selected SRS component
A laser according to claim 37, wherein the said output coupler has a radius of curvature of 50 mm and reflectance of 99.910.05% and 99.510.05% at 1 0610 Ol μm and 1 1810 01 μm respectively
A laser according to claim 37, wherein the said output coupler has a radius of curvature of 50 mm and reflectance of 99.910 05%) and 99.810 05% at 1 35+0 Ol μm and 1 5410 01 μm respectively
A laser according to claim 24, wherein the Q-switch unit is made as active device
A laser according to claim 24, wherein the Q-switch unit is made as passive device
A laser according to claim 41, wherein the said Q-switch unit is made to have an optimum initial transmittance at wavelength of the laser radiation generated on the operational transition of the active element. A laser according to claim 42, wherein the said Q-switch unit is made from a YAG Cr4" crystal with an initial transmittance of 9010 5% at 1 0610 01 μm
A laser according to claim 42, wherein the said Q-switch unit is made from a YAG V " crystal with an initial transmittance of 9610 5% at 1 35+0 01 μm
A laser according to claim 24, wherein the laser active element is made to be broadband, while the components that form the laser cavity are made to be selective restricting the laser action spectral region to a narrow wavelength range with the said selectivity being made variable
The microchip laser with a wavelength conversion comprising a pump source and a cavity formed by an input mirror and an output coupler with an active element disposed between, the cavity length selected so that the transmission bandwidth of the active element is less than the frequency separation of the cavity modes, wherein the active element is made from a material converting the laser radiation generated on it's operational transition to the SRS components
A laser according to claim 46, wherein the pump source is a laser
PCT/BY2000/000004 1999-07-14 2000-06-30 Generation of stimulated raman scattering laser radiation WO2001006606A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU56659/00A AU5665900A (en) 1999-07-14 2000-06-30 Generation of stimulated raman scattering laser radiation
EA200200153A EA003953B1 (en) 1999-07-14 2000-06-30 Generation of stimulated raman scattering lazer radiation

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
BY19990706 1999-07-14
BY19990706 1999-07-14

Publications (1)

Publication Number Publication Date
WO2001006606A1 true WO2001006606A1 (en) 2001-01-25

Family

ID=4083740

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/BY2000/000004 WO2001006606A1 (en) 1999-07-14 2000-06-30 Generation of stimulated raman scattering laser radiation

Country Status (3)

Country Link
AU (1) AU5665900A (en)
EA (1) EA003953B1 (en)
WO (1) WO2001006606A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1235315A2 (en) * 2001-02-27 2002-08-28 Furukawa Co., Ltd. Two-wavelength laser apparatus
WO2006032110A1 (en) * 2004-09-23 2006-03-30 Macquarie University A selectable multiwavelength laser
WO2006058381A1 (en) * 2004-12-01 2006-06-08 Macquarie University External cavity raman laser

Non-Patent Citations (6)

* Cited by examiner, † Cited by third party
Title
"LASER AND NONLINEAR PROPERTIES OF THE POTASSIUM GADOLINIUM TUNGSTATE LASER CRYSTAL KGD(WO4)2:ND3+-(KGW:ND)", OPTICAL ENGINEERING,US,SOC. OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS. BELLINGHAM, vol. 36, no. 6, 1 June 1997 (1997-06-01), pages 1660 - 1669, XP000693513, ISSN: 0091-3286 *
DATABASE INSPEC [online] INSTITUTE OF ELECTRICAL ENGINEERS, STEVENAGE, GB; GRABTCHIKOV A S ET AL: "Stimulated Raman scattering in Nd:KGW laser with diode pumping", XP002153725, Database accession no. 6613881 *
GULIN A V ET AL: "MULTIWAVE GENERATION OF THE STOKES COMPONENTS IN LASERS WITH AN SRS SELF-CONVERTER BASED ON AN ND3+: KGD(WO4)2 CRYSTAL", QUANTUM ELECTRONICS,US,AMERICAN INSTITUTE OF PHYSICS, WOODBURY, NY, vol. 28, no. 9, 1 September 1998 (1998-09-01), pages 804 - 805, XP000788195, ISSN: 1063-7818 *
KAMINSKII A A ET AL: "Raman parametric interactions in KGd(WO4)2 and KGd(WO4)2:Ndmonoclinic crystals: picosecond multicomponent Stokes and anti-Stokes emission and nanosecond stimulated Raman scattering self-conversion into eye-safe 1.5- mu m wavelength range", DOKLADY PHYSICS,US,AMERICAN INSTITUTE OF PHYSICS, WOODBURY, vol. 43, no. 3, March 1998 (1998-03-01), pages 148 - 153-184, XP002113803, ISSN: 1028-3358 *
STANKOV K A ET AL: "HIGH-EFFICIENCY MULTICOLOUR Q-SWITCHED ND3+:KGD(WO4)2 LASER", APPLIED PHYSICS B: LASERS AND OPTICS,DE,SPRINGER INTERNATIONAL, BERLIN, vol. B61, no. 2, 1 August 1995 (1995-08-01), pages 213 - 215, XP000524625, ISSN: 0946-2171 *
THIRD INTERNATIONAL WINTER WORKSHOP ON SPECTROSCOPY AND STRUCTURE OF RARE EARTH SYSTEMS, SZKLARSK POREBA, POLAND, 27 APRIL-1 JUNE 1999, vol. 300-301, Journal of Alloys and Compounds, 12 April 2000, Elsevier, Switzerland, pages 300 - 302, ISSN: 0925-8388 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1235315A2 (en) * 2001-02-27 2002-08-28 Furukawa Co., Ltd. Two-wavelength laser apparatus
EP1235315A3 (en) * 2001-02-27 2005-02-02 Furukawa Co., Ltd. Two-wavelength laser apparatus
WO2006032110A1 (en) * 2004-09-23 2006-03-30 Macquarie University A selectable multiwavelength laser
WO2006058381A1 (en) * 2004-12-01 2006-06-08 Macquarie University External cavity raman laser

Also Published As

Publication number Publication date
AU5665900A (en) 2001-02-05
EA003953B1 (en) 2003-10-30
EA200200153A1 (en) 2003-02-27

Similar Documents

Publication Publication Date Title
CN109950784B (en) Laser and laser radar
US6031854A (en) Diode-pumped cascade laser for deep UV generation
US5121398A (en) Broadly tunable, high repetition rate solid state lasers and uses thereof
US4847850A (en) Continuum generation with miniaturized Q-switched diode pumped solid state laser
CA2750297C (en) Novel photonic devices based on conical refraction
JP2003500861A (en) Passive mode-locked femtosecond laser
US7639721B2 (en) Laser pumped tunable lasers
CN113363798B (en) Adjustable high-optical-efficiency broadband multi-longitudinal-mode Raman microchip laser
CN110582902A (en) Passive Q-switch of diode pumped laser
Kwiatkowski Highly efficient high power CW and Q-switched Ho: YLF laser
WO2001006606A1 (en) Generation of stimulated raman scattering laser radiation
Zayhowski et al. Miniature gain-switched lasers
RU2300834C2 (en) Compact continuous solid-state fcd laser (alternatives)
US7627016B2 (en) Laser pumped tunable lasers
Di Lieto et al. A diode-laser-pumped tunable Ho: YLF laser in the 2 µm region
US11641090B2 (en) High-pulse energy, high-power lasers with diffraction-limited performance
Kuper et al. High-efficiency CW green-pumped alexandrite lasers
Takeda et al. Dual-wavelength operation of a flashlamp pumped narrow-linewidth Ti: sapphire laser
McKinnie et al. The role of active ion concentration in tuned chromium forsterite oscillators
Diettrich et al. Efficient, kHz repetition rate, gain-switched Cr: forsterite laser
Kuper et al. Green pumped alexandrite lasers
Bourliaguet et al. Pulsed OPO brightness improvement by means of intracavity spatial filtering
Hemmer et al. High Performances in Continuous-Wave and Q-switch Operation of a Narrow Linewidth Nd: YVO4 Oscillator Using a Volume Bragg Grating
CN117498134A (en) Femtosecond vortex laser generation device and generation method
Vodchits et al. Multi-wavelength quasi-continuous wave all-solid-state system based on Raman lasers

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AL AM AT AU AZ BA BB BG BR BY CA CH CN CR CU CZ DE DK DM EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG US UZ VN YU ZA ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
WWE Wipo information: entry into national phase

Ref document number: 200200153

Country of ref document: EA

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: JP