Method for fabricating high speed Fabry-Perot lasers for data communication
AssigneeAgere Systems Inc.
InventorsJoseph Michael Freund, George John Przybylek, Dennis Mark Romero, Robert Ewing Behringer
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Abstract
A method for fabricating a Fabry-Perot laser having a cavity length and facet reflectivity product tuned to cause the laser to exhibit a relaxation oscillation frequency of at least 10 GHz, wherein the laser is capable of being modulated at 10 Gb/sec at drive currents between about 20 and 40 mA.
Claims24
A method for fabricating a laser having a Fabry-Perot laser cavity structure, comprising the steps of:
- providing a laser having a cleaved cavity;
- selecting a facet reflectivity product for the laser which will cause the laser to have a relaxation oscillation frequency of at least 10 GHz when a predetermined current bias is applied to the laser, wherein selecting a facet reflectivity product includes measuring the relative intensity noise (RIN) spectrum of at least one conventionally fabricated Fabry-Perot laser having different facet reflectivities when driven at a plurality of current biases different from the predetermined current bias, and using data obtained from RIN spectrum measurements in the equation f r = 1 2 π B 1 L [ I - wL η J · exp [ 1 Γ G o ( α - 1 2 L ln ( 1 R 1 R 2 ) ) - 1 ] ]
- wherein fr is the relaxation oscillation frequency of the laser, w is the width of the laser cavity, h is the quantum efficiency, Jo is the saturation current density, G is the optical confinement factor, a is the distributed loss, Go is the saturation gain, L is the length of the laser cavity, I is the bias current, and R1 and R2 are the reflectivities of the facets, and wherein B is a laser specific constant which can be written as B = Γ dw v η q A
- wherein d is the thickness of the laser cavity and q is the charge of an electron, for determining a facet reflectivity product which will maintain fr at each one of the plurality of current biases;
- and
- applying reflective coatings to the facets, wherein the coatings have reflectivities selected to produce a reflectivity product that is substantially equal to the selected facet reflectivity product.
A method for fabricating a laser having a Fabry-Perot laser cavity structure, comprising the steps of:
- providing a laser having a cavity;
- selecting a laser cavity length and a facet reflectivity product for the laser cavity which will cause the laser cavity to leave a relaxation oscillation frequency of at least 10 GHz wherein a predetermined current bias is applied to the laser, wherein the selecting step includes measuring the relative intensity noise (RIN) spectrum of at least one conventionally fabricated Fabry-Perot laser having different facet reflectivities when drivein at a plurality of current biases different from the predetermined current bias, and using data obtained from the RIN spectrum measurements in the equation f r = 1 2 π B 1 L [ I - wL η J · exp [ 1 Γ G o ( α - 1 2 L ln ( 1 R 1 R 2 ) ) - 1 ] ]
- wherein fr is the relaxation oscillation frequency of the laser cavity, w is the width of the cavity of the laser cavity, h is the quantum efficiency, Jo is the saturation current density, G is the optical confinement factor, a is the distributed loss, Go is the saturation gain, L is the length of the laser cavity, I is the bias current, and R1 and R2 are the reflectivities of the facets, and wherein B is a laser specific constant which can be written as B = Γ dw v η q A
- wherein d is the thickness of the laser cavity and q is the charge of an electron, for determining a facet reflectivity product which will maintain fr at each one of the plurality of current biases;
- cleaving the laser cavity into a bar having opposing facets which define a Fabry-Perot cavity length substantially equal to the selected cavity length;
- applying reflective coatings to the facets, the coatings having reflectivities selected to produce a reflectivity product that is substantially equal to the selected facet reflectivity product.
A method for fabricating a laser having a Fabry-Perot laser cavity structure, the method comprising the steps of:
- providing a laser having a cavity;
- selecting a cavity length for the laser which will cause the laser to have a relaxation oscillation frequency of at least 10 GHz when a predetermined current bias is applied to the laser, wherein the selecting step includes measuring the relative intensity noise (RIN) spectrum of at least one conventionally fabricated Fabry-Perot laser having different facet reflectivities when driven at a plurality of different current biases, and using data obtained from the RIN spectrum measurements in the equation f r = 1 2 π B 1 L [ I - wL η J · exp [ 1 Γ G o ( α - 1 2 L ln ( 1 R 1 R 2 ) ) - 1 ] ]
- wherein fr is the relaxation oscillation frequency of the laser, w is the width of the laser cavity, h is the quantum efficiency, Jo is the saturation current density, G is the optical confinement factor, a is the distributed loss, Go is the saturation gain, written as B = Γ dw v η q A
- wherein d is the thickness of the laser cavity and q is the charge of an electron, for determining a facet reflectivity product which will maintain fr at each of the plurality of different current biases;
- and
- cleaving the laser into a bar having opposing facets which define a Fabry-Perot cavity length substantially equal to the selected cavity length, wherein the facets are uncoated.
A laser comprising a laser bar having opposing facets which define a Fabry-Perot laser cavity structure therebetween, the cavity structure having a length and the facets having a facet reflectivity product which provides the laser with a relaxation oscillation frequency of at least 10 GHz when a predetermined current bias is applied thereto, the facet reflectivity product being selected by measuring the relative intensity noise (RIN) spectrum of at least one conventionally fabricated Fabry-Perot laser having different facet reflectivities when driven at a plurality of current biases different from the predetermined current bias, and using data obtained from RIN spectrum measurements in the equation f r = 1 2 π B 1 L [ I - wL η J · exp [ 1 Γ G o ( α - 1 2 L ln ( 1 R 1 R 2 ) ) - 1 ] ]
- wherein fr is the relaxation oscillation frequency of the laser, w is the width of the laser cavity, h is the quantum efficiency, Jo is the saturation current density, G is the optical confinement factor, a is the distributed loss, Go is the saturation gain, L is the length of the laser cavity, I is the bias current, and R1 and R2 are the reflectivities of the facets, and wherein B is a laser specific constant which can be written as B = Γ dw ν η q A ,
- wherein d is the thickness of the laser cavity and q is the charge of an electron, for determining a facet reflectivity product which will maintain fr at each one of the plurality of current biases.
Dependencies are inferred from the claim text.