Fabry-Perot laser with wavelength control
First Claim
1. A laser device comprising:
- a laser cavity comprising an optical waveguide and facets defining first lasing modes;
a sub-cavity within said laser cavity, said sub-cavity having a predetermined length and being located between said facets, said predetermined sub-cavity length defining second lasing modes having a free spectral range (FSR) that is greater than a FSR of the first lasing modes; and
a plurality of contrast elements adjacent said sub-cavity and having predetermined inter-element separations and predetermined spacings relative to said sub-cavity, said contrast elements interacting with said optical waveguide and forming an aperiodic grating to produce a filtering function for optical radiation propagating in said optical waveguide.
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Accused Products
Abstract
A laser device, in particular a semiconductor laser, emitting optical radiation with a defined mode pattern can be produced from a standard Fabry-Perot (FP) laser by post-processing at the wafer level, i.e. before the wafer is separated into individual dies by cleaving/dicing. A sub-cavity is formed within the FP laser cavity. The sub-cavity has a predetermined length and is located between the FP facets. An aperiodic grating composed of a small number of contrast elements, typically less than 10, with predetermined inter-element separations and predetermined spacings relative to the sub-cavity is formed on or in the optical waveguide. The inter-element separations and the spacings relative to the sub-cavity produce a filtering function of the aperiodic grating for optical radiation propagating in the waveguide. The laser device is suitable for telecommunications applications due to its high side-mode-suppression ratio and narrow-linewidth.
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Citations
31 Claims
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1. A laser device comprising:
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a laser cavity comprising an optical waveguide and facets defining first lasing modes;
a sub-cavity within said laser cavity, said sub-cavity having a predetermined length and being located between said facets, said predetermined sub-cavity length defining second lasing modes having a free spectral range (FSR) that is greater than a FSR of the first lasing modes; and
a plurality of contrast elements adjacent said sub-cavity and having predetermined inter-element separations and predetermined spacings relative to said sub-cavity, said contrast elements interacting with said optical waveguide and forming an aperiodic grating to produce a filtering function for optical radiation propagating in said optical waveguide. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. Method of producing optical radiation with a desired mode structure, comprising:
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producing an optical waveguide capable of propagating said optical radiation;
forming in said optical waveguide a sub-cavity with a predetermined length, said sub-cavity producing a sub-cavity mode structure that overlaps with the desired mode structure; and
forming along said optical waveguide an aperiodic filter having contrast elements, said aperiodic filter filtering the sub-cavity mode structure to generate the desired mode structure, by the acts of;
defining a cost function representing a goodness of fit between the desired mode structure and an actual spectral response of the filter;
assigning to each contrast element of the aperiodic filter at least one characteristic attribute;
generating an initial arrangement of the contrast elements along the optical waveguide;
iteratively modifying at least one characteristic attribute of at least one of the contrast elements and computing for each iteration a cost function;
if the computed cost function for an iteration is less than a predetermined cost function value, selecting a corresponding arrangement of the contrast elements as a desired arrangement of the contrast elements to provide said desired mode structure. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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22. A laser device comprising:
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a laser cavity comprising an optical waveguide and facets;
a sub-cavity within said laser cavity and between said facets; and
a plurality of contrast elements adjacent said sub-cavity and having predetermined inter-element separations and predetermined spacings relative to said sub-cavity so that said contrast elements interact with said optical waveguide and form an aperiodic grating to produce a filtering function for optical radiation propagating in said optical waveguide. - View Dependent Claims (23, 24, 25, 26)
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27. A method for making a laser device comprising:
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forming a sub-cavity within a laser cavity and between facets thereof; and
forming a plurality of contrast elements adjacent said sub-cavity and having predetermined inter-element separations and predetermined spacings relative to said sub-cavity so that said contrast elements interact with said optical waveguide and form an aperiodic grating to produce a filtering function for optical radiation propagating in said optical waveguide. - View Dependent Claims (28, 29, 30, 31)
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Specification