Method and apparatus for wavelength tuning laser diodes
First Claim
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1. A laser source tunable in wavelength with a degenerate self-aligned external cavity comprising:
- an amplifier waveguided medium placed inside the external cavity,a lens assembly to collimate the light from said waveguide amplifier,a reflective volume holographic grating element as the output coupler and the wavelength selective component of the external cavity wherein,said volume holographic grating element has a grating vector substantially non-parallel with respect to the first collimated beam and receives a first and second collimated beam and generates a first and second filtered beam wherein,the first filtered beam is propagating in a direction opposite and substantially non-parallel with respect to the first collimated beam and the second filtered beam is propagating in a direction opposite and substantially parallel to said first collimated beam and providing optical feedback to said waveguide amplifier,a mirror positioned adjacent to said waveguide amplifier wherein,the reflective facet of the mirror is placed at the focal plane of said lens assembly and which receives and reflects said first filtered beam to produce said second collimated beam after collimation from said lens assembly wherein,said second collimated beam produces said second filtered beam upon diffraction from said volume holographic grating element.
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Abstract
A method is presented for shaping the spectral response of volume holographic grating elements by applying controlled thermal energy. The methods allow generating continuous or discontinuous grating periods from a fixed grating period. The methods are applicable to optical feedback into optical sources such as light emitting diodes, lasers and other general optical filtering applications.
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Citations
41 Claims
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1. A laser source tunable in wavelength with a degenerate self-aligned external cavity comprising:
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an amplifier waveguided medium placed inside the external cavity, a lens assembly to collimate the light from said waveguide amplifier, a reflective volume holographic grating element as the output coupler and the wavelength selective component of the external cavity wherein, said volume holographic grating element has a grating vector substantially non-parallel with respect to the first collimated beam and receives a first and second collimated beam and generates a first and second filtered beam wherein, the first filtered beam is propagating in a direction opposite and substantially non-parallel with respect to the first collimated beam and the second filtered beam is propagating in a direction opposite and substantially parallel to said first collimated beam and providing optical feedback to said waveguide amplifier, a mirror positioned adjacent to said waveguide amplifier wherein, the reflective facet of the mirror is placed at the focal plane of said lens assembly and which receives and reflects said first filtered beam to produce said second collimated beam after collimation from said lens assembly wherein, said second collimated beam produces said second filtered beam upon diffraction from said volume holographic grating element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A laser source tunable in wavelength with a degenerate self-aligned external cavity comprising:
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an amplifier waveguided medium placed inside the external cavity, a lens assembly defining an optical axis to collimate the light from the waveguide amplifier to produce a first collimated beam, a polarizing beam-splitter, a quarter-wave plate, a reflective volume holographic grating element as the output coupler and the wavelength selective component of the external cavity wherein said volume holographic grating element first receives said first collimated beam and generates a plurality of filtered beams propagating in a direction opposite and substantially non-parallel with respect to said first collimated beam, a reflecting assembly receiving said plurality of filtered beams reflected from said polarizing beam-splitter and producing a second subset of at least one collimated beam after reflection from said polarizing beam-splitter and collimation from said lens assembly wherein, said second subset of at least one collimated beam produces a second subset of at least one filtered beam upon diffraction from said volume holographic grating element, wherein second subset of at least one filtered beam propagates in a direction substantially parallel to first collimated beam and produces optical feedback into said amplifier waveguided medium. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A laser source tunable in wavelength with a degenerate self-aligned external cavity comprising:
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an amplifier waveguided medium placed inside the external cavity, a first lens assembly defining an optical axis to collimate the light from the waveguide amplifier to produce a first collimated beam, a reflective volume holographic grating element as the output coupler and the wavelength selective component of the external cavity wherein, said volume holographic grating element first receives said first collimated beam and generates a plurality of filtered beams propagating in a direction substantially non-parallel with respect to said first collimated beam, a reflecting assembly receiving said plurality of filtered beams and producing a second subset of at least one collimated beam wherein, said second subset of at least one collimated beam produces a second subset of at least one filtered beam upon diffraction from said volume holographic grating element, wherein second subset of at least one filtered beam propagates in a direction substantially parallel to first collimated beam and produces optical feedback into said amplifier waveguided medium. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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36. A second harmonic laser source comprising:
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a pump laser diode source, an amplifier medium whose facet facing said pump laser diode forms one side of the fundamental cavity, a non-linear material to generate second harmonic light positioned adjacent to said amplifier medium whose facet opposite said amplifier medium is the output coupler of the fundamental cavity, a first lens assembly to collimate the light from said pump laser diode, a reflective volume holographic grating element as the output coupler of the external cavity of said pump laser diode source and the wavelength selective component of the pump external cavity wherein said grating element receives a first and second collimated beam from said laser diode pump and generates a first and second filtered beam wherein the first filtered beam is propagating in a direction opposite and substantially non-parallel to the first collimated beam and the second filtered beam is propagating in direction opposite and substantially parallel to said first collimated beam and provides optical feedback to said laser diode pump, a mirror positioned adjacent to said laser diode pump whose reflective facet is placed at the focal plane of said first lens assembly and which receives and reflects said first filtered beam to produce a second collimated beam after collimation from said lens assembly, wherein second collimate beam produces said second filtered beam upon diffraction from said volume holographic grating element, a second lens assembly to form a beam expander with first lens assembly for the second harmonic light. - View Dependent Claims (37, 38, 39, 40, 41)
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Specification