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US 6,597,718 B2Granted
Electroabsorption-modulated fabry perot laser
AssigneeMultiplex Company, Inc.
InventorsTawee Tanbun-Ek, Won-Tien Tsang, Liang David Tzeng
Life of this patent
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Abstract
An electroabsorption modulated laser (EML) is formed to include a Fabry-Perot lasing section, in place of the conventional DFB lasing section. When operated at a wavelength of 1310 nm, the wider spectral bandwidth of the FP device (containing several longitudinal modes) is of no concern, since 1310 nm is the zero dispersion wavelength of most conventional transmission fibers. A selective area growth process is used to simultaneously form the MQW active regions of both the FP and EA sections of the EML device, and an isolation trench may be formed between the sections to reduce the effects of electrical crosstalk.
Claims17
An electroabsorption modulated laser comprising:
- an InP substrate;
- a Fabry-Perot (FP) laser device section comprising a first cladding layer deposited on said InP substrate, a first multiple quantum well (MQW) active region deposited on said first cladding layer and comprising a plurality of barrier layers and a plurality of well layers, a second cladding layer deposited on said first MQW active region, and an electrical contact layer deposited on said second cladding layer, wherein a first electrical contact pad is in electrical communication with said second cladding layer;
- an electroabsorption (EA) modulator section comprising said first cladding layer deposited on said InP substrate, a second MQW active region deposited on said first cladding layer and comprising a plurality of barrier layers and a plurality of well layers, said second cladding layer deposited on said second MQW active region, and said electrical contact layer deposited on said second cladding layer, wherein a second electrical contact pad is in electrical communication with said second cladding layer;
- a FP laser endface;
- and
- an EA modulator endface;
- wherein said first MQW active region is optically coupled to said second MQW active region;
- wherein said FP laser endface comprises a first reflective coating and said BA modulator endface comprises a first anti-reflective coating;
- wherein said first reflective coating and said first anti-reflective coating form a Fabry-Perot cavity;
- and
- wherein each of said barrier layers and said well layers of said first MQW region are thicker than each of said barrier layers and said well layers of said second MQW active region, respectively.
8 more elements
A method for making a Fabry-Perot electroabsorption modulated laser, the method comprising the steps of:
- a) providing an InP substrate including a top major surface;
- b) covering said InP substrate top major surface with a masking layer;
- c) etching a stripe in said masking layer to define the region wherein said laser will be formed;
- d) depositing a first cladding layer comprising n-InP in the exposed stripe;
- e) depositing a first separate confinement heterostructure (SCH) layer of InGaAsP to cover said first cladding layer;
- f) forming a first MQW structure active region for a Fabry-Perot (FP) laser and a second MQW structure active region for an electroabsorption (EA) modulator on said first SCH layer, wherein said first MQW active region is optically coupled to said second MQW active region and said FP laser region exhibits thicker barrier and well layers than said EA modulator barrier and well layers;
- g) depositing a second SCH layer of InGaAsP to cover said MQW structures;
- h) removing the remaining mask layer and growing Fe-doped InP current blocking regions on the exposed substrate surface to be coextensive with said second SCH InGaAsP layer;
- i) depositing a second cladding layer comprising p-InP to cover said Fe-doped InP current blocking regions and said second SCH InGaAsP layer, wherein said second cladding layer is covered with a contact layer of p-InGaAs;
- and
- j) forming a first electrical contact pad on said p-InGaAs contact layer in the area of said FP laser and a second electrical contact pad on said p-InGaAs contact layer in the area of said EA modulator.
8 more elements
A method for making a Fabry-Perot electroabsorption modulated laser, the method comprising the steps of:
- a) providing an InP substrate including a top major surface;
- b) covering said InP substrate top major surface with a masking layer;
- c) etching a stripe in said masking layer to define the region wherein said laser will be formed;
- d) depositing a first cladding layer comprising n-InP in the exposed stripe;
- e) depositing a first separate confinement heterostructure (SCH) layer of InGaAsP to cover said first cladding layer;
- f) forming a first MQW structure active region for a Fabry-Perot (FP) laser and a second MQW structure active region for an electroabsorption (EA) modulator on said first SCH layer, wherein said first MQW active region is optically coupled to said second MQW active region and said FP laser region exhibits thicker barrier and well layers than said BA modulator barrier and well layers;
- g) depositing a second SCH InGaAsP layer to cover said MQW structures;
- h) removing the remaining mask layer and growing Fe-doped InP current blocking regions on the exposed substrate surface to be coextensive with said second SCH InGaAsP layer;
- i) depositing a second cladding layer comprising p-InP to cover said Fe-doped InP current blocking regions and said second SCH InGaAsP layer, wherein said second cladding layer is covered with a contact p-InGaAs layer;
- j) forming a first electrical contact pad on said p-InGaAs contact layer in the area of said FP laser and a second electrical contact pad on said p-InGaAs contact layer in the area of said EA modulator;
- and
- k) forming a first reflective coating on a FP laser endface and a first anti-reflective coating on an EA modulator endface.
9 more elements
Dependencies are inferred from the claim text.