Suppression of phototransistor gain in an optical modulator
AssigneeCiena Corporation
InventorsBehnood Ghohroodi Ghamsari, Alasdair Rankin
Life of this patent
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Abstract
An optical modulator includes an emitter layer with N-type doping having a first bandgap energy; a base layer with P-type doping having a second bandgap energy; a sub-emitter layer disposed between the emitter layer and the base layer, wherein the sub-emitter layer has a third bandgap energy that is less than both the first bandgap energy and the second bandgap energy. The sub-emitter layer provides a barrier to electrons flowing from the emitter layer, while allowing photo-generated holes to recombine in the sub-emitter layer thereby mitigating current amplification.
Claims18
An optical modulator comprising:
- an emitter layer with N-type doping having a first bandgap energy;
- a base layer with P-type doping having a second bandgap energy;
- a sub-emitter layer disposed between the emitter layer and the base layer, wherein the sub-emitter layer has a third bandgap energy that is less than both the first bandgap energy and the second bandgap energy;
- a collector layer having n-type doping;
- and
- an undoped layer disposed between the collector layer and the base layer, wherein the undoped layer is configured to have light propagate through the undoped region for modulation thereof.
A method of forming an optical modulator comprising steps of:
- forming an emitter layer with N-type doping having a first bandgap energy;
- forming a base layer with P-type doping having a second bandgap energy;
- forming a sub-emitter layer disposed between the emitter layer and the base layer, wherein the sub-emitter layer has a third bandgap energy that is less than both the first bandgap energy and the second bandgap energy;
- forming a collector layer having n-type doping;
- and
- forming an undoped layer disposed between the collector layer and the base layer, wherein the undoped layer is configured to have light propagate through the undoped region for modulation thereof.
Dependencies are inferred from the claim text.