EP0378061A2
Expired / Lapsed
EP
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Apparatus and method for producing blue-green light radiation
Assignee: International Business Machines Corp
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Filing: 1989-12-18
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Granted: —
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Expires: 2009-12-18
Abstract
Abstract Apparatus and method for producing coherent blue-green-light radiation having a wavelength of essentially 490-500 nm. A diode laser (10), such as a strained-layer InGaAs/GaAs diode laser, provides a 980-1,000 nm beam (12), and a nonlinear crystal (19) of KTP (KTiOPO₄) produces coherent radiation (22) by noncritically phase-matched second-harmonic generation (SHG) of said beam. The beam preferably has a wavelength of essentially 994 nm for generating radiation having a wavelength of essentially 497 nm. The crystal is disposed within an optical resonator (18) and the frequency of the laser is locked to that of the resonator. Alternatively, two diode lasers (10,11) are oriented to provide orthogonally polarized beams each with a wavelength of 980-1,000 nm but within essentially 1 nm of each other, and the KTP crystal is oriented with its a and c axes parallel to the orthogonally polarized beams. The KTP crystal may have an associated optical waveguide along which the beam is propagated to enhance SHG efficiency.
Inventors
- 👤 Christoph Stephan Harder
- 👤 Wilfried Lenth
- 👤 Heinz Peter Meier
- 👤 William Paul Risk
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 00:00
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/06; H01S5/068; H01S5/0683; H01S5/0687; G; G02; G02F; G02F1/00; G02F1/35; G02F1/37; G02F1/353; G02F1/3542; H01S5/40; H01S5/4025
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
61 words
Apparatus for producing coherent blue-green-light radiation having a wavelength of essentially 490-500 nm, comprising: at least one diode laser (10, 11, 40, 52, 60) for providing an essentially 980-1,000 nm beam (12, 13, 41, 53, 61); and a nonlinear crystal (19, 44, 51, 64) of essentially KTiOPO₄ (KTP) which produces the coherent radiation by noncritically phase-matched second-harmonic generation of said beam.
Claim 2
Dependent Claim
61 words
Apparatus for producing coherent blue-green-light radiation having a wavelength of essentially 490-500 nm, comprising: at least one diode laser (10, 11, 40, 52, 60) for providing an essentially 980-1,000 nm beam (12, 13, 41, 53, 61); and a nonlinear crystal (19, 44, 51, 64) of essentially KTiOPO₄ (KTP) which produces the coherent radiation by noncritically phase-matched second-harmonic generation of said beam.
Claim 3
Dependent Claim
16 words
The apparatus of claim 1, wherein the diode laser is a strained layer InGaAs/GaAs diode laser.
Claim 4
Dependent Claim
25 words
The apparatus of claim 1, wherein the beam has a wavelength of essentially 994 nm for generating radiation having a wavelength of essentially 497 nm.
Claim 5
Dependent Claim
26 words
The apparatus of claim 1, including a resonator (18, 45, 65) resonant at a wavelength of essentially 980-1,000 nm and in which said crystal is disposed.
Claim 6
Dependent Claim
30 words
The apparatus of claim 4, including means (20, 21, 46, 47, 66, 67) for matching the frequency of the essentially 980-1,000 nm beam to the resonant frequency of the resonator.
Claim 7
Dependent Claim
27 words
The apparatus of claim 1, wherein the crystal is disposed within an optical resonator and the frequency of the laser is matched to that of the resonator.
Claim 8
Dependent Claim
35 words
The apparatus of claim 1, including means providing a pair of reflectors (20, 21, 46, 47, 66, 67) disposed ad jacent opposite sides of the crystal, said reflectors having facing surfaces that reflect said beam.
Claim 9
Dependent Claim
18 words
The apparatus of claim 1, wherein the coherent radiation is propagated along the b axis of said crystal.
Claim 10
Dependent Claim
23 words
The apparatus of claim 1, including: a resonator resonant at a wavelength of essentially 490-500 nm and in which said crystal is disposed.
Claim 11
Dependent Claim
23 words
The apparatus of claim 9, including means for matching the frequency of the second-harmonic radiation generated to the resonant frequency of the resonator.
Claim 12
Dependent Claim
64 words
The apparatus of claim 1, including two diode lasers oriented to provide orthogonally polarized beams of essentially 980-1,000 nm, the wavelengths of each beam being within essentially 1 nm of each other, and wherein the nonlinear crystal is oriented with its a- and c- axes parallel to said orthogonally polarized beams for producing the coherent radiation by noncritically phase-matched second-harmonic generation of said beam.
Claim 13
Dependent Claim
25 words
The apparatus of claim 11, wherein both beams have a wavelength of essentially 994 nm for generating radiation having a wavelength of essentially 497 nm.
Claim 14
Dependent Claim
32 words
The apparatus of claim 11, wherein the crystal is disposed within an optical resonator and the frequency of each laser is maintained at a preselected value relative to that of the resonator.
Claim 15
Dependent Claim
36 words
The apparatus of claim 11, including means providing a pair of reflectors disposed adjacent opposite sides of the crystal, said reflectors having facing surfaces that reflect said beam and nonfacing surfaces that pass the coherent radiation.
Claim 16
Dependent Claim
67 words
The apparatus of claim 11, including locking means comprising: means for each laser for generating a signal indicative of deviations in the frequency of that laser beam from a respective preselected frequency; and means, including feedback means, for each laser for controlling the temperature and/or injection current of that laser beam according to variations in said signal to maintain the laser beam at its respective preselected frequency.
Claim 17
Dependent Claim
64 words
The apparatus of claim 1 and 6, including: two diode lasers outboard of the resonator and providing beams of essentially 980-1,000 nm; means, including polarizing beamsplitter means, for combining the two laser beams; and means for locking the frequencies of the two laser beams to the resonant frequencies for the modes of the resonator polarized along the a- and c- axes of said crystal.
Claim 18
Dependent Claim
24 words
The apparatus of claim 1 and 8, wherein said beam is polarized at essentially 45° to the a- and c- axes of said crystal.
Claim 19
Dependent Claim
42 words
The apparatus of claim 17, wherein said crystal forms part of a resonator resonant at said second harmonic; and including means for tuning said beam so that the coherent radiation produced is frequency locked to match the resonant frequency of said resonator.
Claim 20
Dependent Claim
36 words
The apparatus of claim 1, wherein said nonlinear crystal has an optical waveguide oriented such that the beam is propagated along said waveguide for generating the coherent radiation by noncritically phase-matched second-harmonic generation of said beam.
Claim 21
Dependent Claim
147 words
Apparatus for producing coherent blue-green-light radiation having a wavelength of essentially 490-500 nm, comprising: a diode laser (60) with collimation optics providing a linearly polarized beam of essentially 980-1,000 nm; an optical resonator (65) comprising a nonlinear crystal (64) and a phaseplate (69), said nonlinear crystal being of essentially KTP and oriented with its b-axis parallel to said beam and its a- and c- axes at an angle of essentially 45 degrees to the polarization of said beam; said phaseplate being disposed inside the resonator and oriented such that the polarization of the essentially 980-1,000 nm radiation is at an angle of essentially 45 degrees with respect to the a- and c- axes of the crystal when it re-enters said crystal after a round-trip pass through the resonator; and means (62, 71) for locking the frequency of the diode laser to a resonant frequency of the resonator.
Claim 22
Dependent Claim
147 words
Apparatus for producing coherent blue-green-light radiation having a wavelength of essentially 490-500 nm, comprising: a diode laser (60) with collimation optics providing a linearly polarized beam of essentially 980-1,000 nm; an optical resonator (65) comprising a nonlinear crystal (64) and a phaseplate (69), said nonlinear crystal being of essentially KTP and oriented with its b-axis parallel to said beam and its a- and c- axes at an angle of essentially 45 degrees to the polarization of said beam; said phaseplate being disposed inside the resonator and oriented such that the polarization of the essentially 980-1,000 nm radiation is at an angle of essentially 45 degrees with respect to the a- and c- axes of the crystal when it re-enters said crystal after a round-trip pass through the resonator; and means (62, 71) for locking the frequency of the diode laser to a resonant frequency of the resonator.
Claim 23
Independent Claim
47 words
A method for producing coherent blue-green-light radiation having a wavelength of essentially 490-500 nm, comprising the steps of: using a diode laser, providing an essentially 980-1,000 nm beam; and producing said radiation by noncritically phase-matched second-harmonic generation of said beam in a nonlinear crystal of essentially KTP.
Claim 24
Independent Claim
47 words
A method for producing coherent blue-green-light radiation having a wavelength of essentially 490-500 nm, comprising the steps of: using a diode laser, providing an essentially 980-1,000 nm beam; and producing said radiation by noncritically phase-matched second-harmonic generation of said beam in a nonlinear crystal of essentially KTP.
References Cited (Backward Citations)
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