WO2007085982A2 - Système laser de conversion-élévation co-dopé - Google Patents

Système laser de conversion-élévation co-dopé Download PDF

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Publication number
WO2007085982A2
WO2007085982A2 PCT/IB2007/050153 IB2007050153W WO2007085982A2 WO 2007085982 A2 WO2007085982 A2 WO 2007085982A2 IB 2007050153 W IB2007050153 W IB 2007050153W WO 2007085982 A2 WO2007085982 A2 WO 2007085982A2
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WO
WIPO (PCT)
Prior art keywords
laser
dopant
doped
laser system
host material
Prior art date
Application number
PCT/IB2007/050153
Other languages
English (en)
Other versions
WO2007085982A3 (fr
Inventor
Ulrich Weichmann
Gero Heusler
Original Assignee
Philips Intellectual Property & Standards Gmbh
Koninklijke Philips Electronics N.V.
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 Philips Intellectual Property & Standards Gmbh, Koninklijke Philips Electronics N.V. filed Critical Philips Intellectual Property & Standards Gmbh
Publication of WO2007085982A2 publication Critical patent/WO2007085982A2/fr
Publication of WO2007085982A3 publication Critical patent/WO2007085982A3/fr

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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
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/094003—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light the pumped medium being a fibre
    • 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
    • H01S3/17—Solid materials amorphous, e.g. glass
    • 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
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/094092—Upconversion pumping
    • 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
    • H01S3/1601—Solid materials characterised by an active (lasing) ion
    • H01S3/1603—Solid materials characterised by an active (lasing) ion rare earth
    • 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
    • H01S3/1601—Solid materials characterised by an active (lasing) ion
    • H01S3/1603—Solid materials characterised by an active (lasing) ion rare earth
    • H01S3/1608—Solid materials characterised by an active (lasing) ion rare earth erbium
    • 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
    • H01S3/1601—Solid materials characterised by an active (lasing) ion
    • H01S3/1603—Solid materials characterised by an active (lasing) ion rare earth
    • H01S3/1615—Solid materials characterised by an active (lasing) ion rare earth samarium
    • 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
    • H01S3/17—Solid materials amorphous, e.g. glass
    • H01S3/173—Solid materials amorphous, e.g. glass fluoride glass, e.g. fluorozirconate or ZBLAN [ ZrF4-BaF2-LaF3-AlF3-NaF]

Definitions

  • a co-doped upconversion laser system comprising a host- material, whereas the host material is made of at least one crystal material and /or at least one glass material, which features a low phonon energy, whereas said host material comprises at least one dopant made of Erbium (Er 3+ ), which is pumped by laser light with a single wavelength in the infrared wavelength range, whereas said host material furthermore comprises at least one co-dopant.
  • Er 3+ Erbium
  • Upconversion lasers are suitable systems to fulfil most of the requirements and attracted a lot of attention in the research regarding optical light sources.
  • the basic principle requires the successive absorption of two or more pump photons via intermediate long-lived levels, followed by the emission of laser radiation at a shorter wavelength than the pump wavelength.
  • Rare earth ions are used for such lasers.
  • Special consideration deserves the proper choice of host materials. These should be characterised by low phonon energies, which is a requirement for the long lifetime of the intermediate levels as well as for the laser level.
  • most upconversion lasers were realised in ZBLAN-glass as a host material.
  • the US Patent 6 510 276 Bl describes a highly doped waveguide, which comprises a waveguide having a dopant disposed therein, said dopant having a concentration of between 1,001 and 500.000 ppm, and wherein said waveguide contains clusters of said dopant, wherein at least 50% of said dopant is in said clusters and wherein said clusters of said dopant enhance cross-relaxation between two elements of said dopant, whereas said dopant is Erbium (Er).
  • Erbium Erbium
  • An optical amplifier and laser is disclosed in the United States Patent US 5 617 244 with a resonant cavity defined by a pair of mirrors butted to respective ends of a fluorozirconate optical fibre.
  • the fibre has a numerical aperture of 0.205 and a LPn mode cut-off of about 2.0 ⁇ m.
  • the fibre is co- doped with Thulium ions to a concentration of about 0.1% and with Terbium ions to a concentration of about 1%.
  • An optical pump source provides a pump signal at 775nm which excites the Thulium ions into the 1 G 4 energy level to provide lasing at about 475nm.
  • the pump source is preferably a high power semiconductor laser.
  • the EnZBLAN laser whereby the doping ion is Erbium (Er).
  • the laser is pumped by the resonant absorption of two infrared photons of similar wavelength.
  • the intermediate state is the 4 Ii i /2 and the upper pump level is the 4 F 7Z2 level. From this upper pump level non- radiative population transfer to the 4 S 3/2 - level occurs, which serves as the upper laser level for laser emission at 550nm to the ground state 4 Ii 5/2 .
  • ESA At first excited state absorption (ESA) towards higher lying levels can lead to the emission of UV-radiation and the subsequent formation of colour centres in the host material.
  • Tm:ZBLAN lasers Such phenomena are described for Tm:ZBLAN lasers and were also observed in EnZBLAN lasers.
  • the consequence of colour centres is an increased threshold and decreased conversion efficiency for the laser.
  • the lower laser level is one of the sublevels of the ground state. Therefore the laser is effectively a three level laser and re-absorption of the laser radiation may occur, which decreases the efficiency of the material system.
  • the EnZBLAN laser is most efficient in the green wavelength range around 550nm. Laser operation at other wavelengths in the visible requires the excitation of higher lying electronic states, which is not efficiently possible by using said material system.
  • the invention has the objective to eliminate the above-mentioned disadvantages.
  • said host material comprises at least one co- dopant made of Terbium (Tb 3+ ) or Samarium (Sm 3+ ), in order to emit laser radiation in the range of at least one visible wavelength.
  • Tb 3+ Terbium
  • Sm 3+ Samarium
  • the corresponding material combination leads to different advantages.
  • the co-dopands are characterized by a large energy gap between the respective upper laser level and the next lower level. This has the consequence, that the upper laser levels are not depopulated by non- radiative energy transfer and exhibit a long lifetime. This situation is much more favourable than the situation in the pure Er- system.
  • the dopant Erbium (Er) is combined with the co-dopant
  • Tb Terbium
  • Sm Samarium
  • the material combination according to the present invention leads to the possibility of laser operation at different wavelengths in the visible wavelength range. To achieve this in the pure EnZBLAN laser is rather involved and implies the excitation of higher lying levels.
  • Tb- and Sm-co-doped EnZB LAN-lasers other wavelengths are available, where in the Sm-laser a wavelength can be generated that is very close to the well-known Na-D-lines.
  • the Tb- co- doping system features the advantage, that not only the Ar-ion- laser wavelength at 488nm, but also the three primaries for RGB can be obtained.
  • the Tb-codoped EnZBLAN - laser is therefore an ideal candidate to be applied as a light source for display applications.
  • the Tb co- doped system leads to a further advantage as compared to the pure EnZBLAN laser.
  • Several states of Er with energies above 3eV are in resonance with Tb-levels. Energy transfer between these two systems helps to avoid the population of high-lying levels that lead to the emission of UV-radiation and subsequent formation of colour centres.
  • Co-doping of the E ⁇ ZBLAN-laser with Tb is therefore an effective way to circumvent the problem of photo-bleaching.
  • the host material is made of the group of crystal materials characterized by relatively low phonon energies, comprising Y 2 O 2 , YLF, YAP, YAG, - material, which means, that the range of suitable materials is enlarged.
  • the upconversion laser material is brought to the form of a waveguide, whereas the waveguide is formed as a fiber or a planar waveguide.
  • the system may be applied in many different fields comprising fiber systems or waveguides for micro-systems or projection systems.
  • the co- dopants Terbium (Tb) and /or Samarium (Sm) feature a doping level comprising a factor of 0.1 to 10 related to the doping level of the dopant Erbium (Er). Both, the dopant Er as well as the co-dopants Tb or Sm are in their triple-ionic state.
  • the co- doped upconversion laser system mentioned above can be used in a variety of applications amongst them systems being data storage systems, display technology, undersea communications, fibre-optics applications as well as projection systems.
  • Fig. 1 shows the energy level diagram of a co- doped upconversion laser system with a dopant Erbium (Er 3+ ) as an exciting material and a Terbium (Tb 3+ ), used for the laser transition; and
  • Fig. 2 shows the energy level diagram of a co- doped up-conversion laser system with a dopant Erbium (Er 3+ ) as an exciting material and a co-dopant Samarium (Sm 3+ ), used for the laser transition.
  • Figure 1 shows the energy level diagram 1 of Er/Tb co- doping and figure 2 shows the energy level diagram 13 of Er/Sm co- doping.
  • an excitation energy scale 11 On the left side of the scheme is shown an excitation energy scale 11 and on the right side is shown the wave number 10.
  • the co-dopants Sm and Tb can easily be excited via the Er 4 F 7/2 -state at about 21000cm "1 , whereas the Er- dopant is at first excited from the ground state 2 by a ground state absorption (GSA) 3 to a first excitation level 5, followed by a subsequent excited state absorption (ESA) 4 to a second excitation level 6.
  • GSA ground state absorption
  • ESA subsequent excited state absorption
  • the energy level diagrams 1, 13 feature a non-radiative transition 7 to the exited state of the co-dopant, whereas the laser transitions in Sm couple the 4 Gs /2 - level with H-states and the 5 D 4 -state with F-states in the case of Tb. These transitions should therefore be much more probable than the laser transition in Er, where the 4 S 3/2 -level is coupled with the 4 Ii 5/2 -level. Therefore the laser action according to the laser transition 8, 8a, 8b and 8c occurs entirely in the co-dopand, while the laser pumping is done via the Er-ion, indicated by the ground state absorption 3 and the excited state absorption 4.
  • This excitation scheme is somewhat comparable to the He/Ne-laser and provides the advantage of a true four-level-laser scheme.
  • the laser transitions 8, 8a, 8b and 8c occur between the co- dopant excited state and the lower laser level 9, 9a, 9b.
  • the transition between one of the lower laser levels 9, 9a, 9b and the ground state 2 are characterised by a non- radiative relaxation 12, whereas the relaxation 12 is featured by a fast relaxation. Thereby a four level laser scheme is realised.
  • EnZBLAN laser is rather involved and implies the excitation of higher lying levels.
  • Tb- and Sm-co-doped EnZB LAN-lasers other wavelengths are available, whereas in the Sm-laser a wavelength can be generated that is very close to the well-known Na-D- lines and in the Tb-codoped system, red, green and blue wavelengths can be generated as shown in Fig. 1.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Optics & Photonics (AREA)
  • Lasers (AREA)
  • Semiconductor Lasers (AREA)

Abstract

L'invention concerne un système laser de conversion-élévation co-dopé qui comprend un matériau hôte, ledit matériau hôte étant composé d'au moins un matériau cristallin et/ou d'un matériau vitreux et présentant une faible énergie de phonons. Ledit matériau hôte comprend un dopant composé d'erbium (Er3+), qui est pompé par de la lumière laser à une longueur d'onde unique dans la plage de longueur d'onde infrarouge. Ledit matériau hôte comprend également au moins un co-dopant composé de terbium (Tb3+) ou de samarium (Sm3+), afin d'émettre un rayonnement de lumière laser dans la plage d'au moins une longueur d'onde visible. Le système de l'invention permet d'obtenir un système laser de conversion-élévation co-dopé assurant une élimination de centres colorés, une réabsorption réduite du rayonnement laser et l'émission de lumière laser dans la plage de longueurs d'ondes visibles.
PCT/IB2007/050153 2006-01-26 2007-01-17 Système laser de conversion-élévation co-dopé WO2007085982A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP06100894 2006-01-26
EP06100894.2 2006-01-26

Publications (2)

Publication Number Publication Date
WO2007085982A2 true WO2007085982A2 (fr) 2007-08-02
WO2007085982A3 WO2007085982A3 (fr) 2007-10-18

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TWI497850B (zh) * 2012-11-09 2015-08-21 Ind Tech Res Inst 雷射裝置及產生雷射光的方法

Citations (1)

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Publication number Priority date Publication date Assignee Title
US6510276B1 (en) 1998-05-01 2003-01-21 Science & Technology Corporation @ Unm Highly doped fiber lasers and amplifiers

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US5295146A (en) * 1992-04-10 1994-03-15 Polaroid Corporation Solid state gain mediums for optically pumped monolithic laser
JPH09162470A (ja) * 1995-12-13 1997-06-20 Nec Corp ２波長レーザ発振器
US6490309B1 (en) * 1999-07-21 2002-12-03 Fuji Photo Film Co., Ltd. Laser-diode-pumped laser apparatus in which Pr3+-doped laser medium is pumped with GaN-based compound laser diode
US6821917B2 (en) * 2002-06-14 2004-11-23 The University Of Southampton Tellurite glass and applications thereof
ATE409889T1 (de) * 2005-01-04 2008-10-15 Koninkl Philips Electronics Nv Wellenlängenkonversionsschichten mit eingebetteten kristalliten

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6510276B1 (en) 1998-05-01 2003-01-21 Science & Technology Corporation @ Unm Highly doped fiber lasers and amplifiers

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WO2007085982A3 (fr) 2007-10-18
TW200740059A (en) 2007-10-16

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