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US 6,956,232 B2Granted
Electroabsorption modulator
AssigneeTriQuint Technology Holding Co.
InventorJoseph P. Reynolds
Life of this patent
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Abstract
A semiconductor modulator is disclosed which exhibits a negative alpha parameter at low operating bias. The device includes at least two barrier layers with a quantum well layer therebetween. An additional layer is formed adjacent to the quantum well layer, the additional layer having a bulk bandgap energy greater than the quantum well layer so as to form a stepped well between the barrier layers.
Claims14
A semiconductor optical modulator whose absorption of light varies as an operating electrical bias is applied, the modulator comprising:
- first and second semiconductor layers comprising materials having first and second bulk bandgap energies, respectively;
- third and fourth semiconductor layers formed between the first and second layers, and comprising materials having third and fourth bulk bandgap energies which are both less than the first and second bulk bandgap energies, the fourth layer having a bulk bandgap energy which is greater than that of the third layer so as to form in combination with the third layer a stepped quantum well between the first and second layers, the stepped quantum well of the third and fourth layers being such as to produce an alpha parameter which is negative at a low operating bias for the device.
A method of modulating light comprising:
- providing a semiconductor optical modulator with a stepped quantum well structure between barrier layers in the path of the light;
- and
- applying an operating electrical bias to the modulator to vary the light absorption of the modulator, the electrical bias being such that the modulator exhibits only a negative alpha parameter over essentially the entire range of operating voltage.
Dependencies are inferred from the claim text.