Increasing the yield of precise wavelength lasers
First Claim
1. A method of increasing the yield of semiconductor laser devices comprising the steps of:
- a. forming a layered structure on a wafer exhibiting a material gain function region capable of sustaining oscillation at a number of F-P modes, said material gain function normally giving rise to oscillation at a wavelength of λ
2; and
b. etching a second-order grating on one of the layers of said structure lying wholly in an unpumped area outside said gain region of said structure where the optical field strength is sufficient to provide feedback to stabilize the wavelength at λ
1 without creating surface diffraction loss greater than 5 %;
c. forming a dielectric material layer, instead of semiconductor epitaxial layers, in direct contact with and overlying the length of said grating.
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Accused Products
Abstract
A wafer supporting a semiconductor structure having a material gain function that would preferentially support an Fabry-Perot laser mode at an unwanted wavelength λ2 is provided with a second-order dielectric grating located sufficiently remotely from the high intensity optical field of the quantum well and the waveguide layers to receive just enough transverse mode energy to provide feedback to reduce the gain at λ2 and support oscillation at a desired wavelength λ1. More particularly, by locating the grating in an unpumped area not requiring epitaxial overgrowth and so as to provide a gain discrimination factor Δg≈0.1 cm−1 at the desired wavelength λ1, the fraction of power lost to transverse mode radiation can be held to about 1% which is sufficient to provide stabilizing feedback without sapping too much energy from the longitudinal beam.
18 Citations
14 Claims
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1. A method of increasing the yield of semiconductor laser devices comprising the steps of:
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a. forming a layered structure on a wafer exhibiting a material gain function region capable of sustaining oscillation at a number of F-P modes, said material gain function normally giving rise to oscillation at a wavelength of λ
2; and
b. etching a second-order grating on one of the layers of said structure lying wholly in an unpumped area outside said gain region of said structure where the optical field strength is sufficient to provide feedback to stabilize the wavelength at λ
1 without creating surface diffraction loss greater than 5 %;
c. forming a dielectric material layer, instead of semiconductor epitaxial layers, in direct contact with and overlying the length of said grating. - View Dependent Claims (2, 3)
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4. A method of increasing the yield of semiconductor laser devices giving rise to oscillation at a wavelength of λ
- 1, comprising the steps of;
a. forming a layered structure including a quantum well and waveguide layers on a wafer exhibiting a material gain function region capable of sustaining oscillation at various F-P modes, said material gain function normally giving rise to oscillation at a wavelength of λ
2;
b. creating a second-order grating outside said gain region to stabilize longitudinal emission at a wavelength of λ
1 without creating a surface diffraction loss greater than 5%;
c. forming a dielectric material layer, instead of semiconductor epitaxial layers, in direct contact with and overlying the length of said grating. - View Dependent Claims (5, 6, 7)
- 1, comprising the steps of;
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8. A method of increasing the yield of semiconductor laser devices comprising the steps of:
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a. forming on a wafer a layered structure including a quantum well and waveguide layers exhibiting a material gain function capable of sustaining oscillation at a number of F-P modes, said structure having a material gain function normally giving rise to oscillation at a wavelength of λ
2;
b. etching one of said layers in a process including blue light holography to produce a second-order grating thereon;
said one of said layers being located away from said quantum well and waveguide layers in an unpumped area outside the gain region so as to receive sufficient fringe field strength to provide a feedback gain discrimination factor α
having a value of approximately 1.0 cm−
1 between wavelengths of λ
2 and λ
1.
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9. A method of increasing the yield of semiconductor laser devices giving rise to oscillation at a wavelength of λ
- 1, comprising the steps of;
a. forming a layered structure including a quantum well and waveguide layers on a wafer exhibiting a material gain function capable of sustaining oscillation at a number of F-P modes, said material gain function having a tendency to give rise to oscillation at a wavelength of λ
2;
b. etching a surface relief portion through said layers exhibiting said gain function at a point beyond the end of the quantum well gain strip to effect an unpumped region; and
c. creating a second-order grating in said unpumped region outside the gain region where the field strength is less than one thousandth of the field strength of the quantum well and waveguide layers, said grating providing a gain discrimination factor α
having a value of approximately 1.0 cm−
1 between wavelengths of λ
2 and λ
1.- View Dependent Claims (10, 11)
- 1, comprising the steps of;
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12. A semiconductor laser device comprising:
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a negatively doped semiconductor material substrate;
a plurality of semiconductor material epitaxial layers and a laser gain stripe;
a second-order grating etched into one of said semiconductor material epitaxial layers, said grating having a plurality of grating grooves for providing feedback to stabilize the of emission of laser light at desired wavelength from an emitting facet of said laser;
said grating wholly lying in an unpumped region of said laser beyond at least one end of said gain stripe; and
in direct contact witha dielectric material layer instead of semiconductor epitaxial layers overlying the length of said grating. - View Dependent Claims (13, 14)
a stop etch layer;
a negatively doped GaAs layer;
a negatively doped aluminum, gallium and arsenic material compound (AlGaAs) cladding layer;
a negatively doped AlGaAs confinement layer;
a AlGaAs active layer; and
a positively doped AlGaAs cladding layer.
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Specification