US 5,329,136 AGranted

Voltage-tunable photodetector

AssigneeAT&T Bell Laboratories

InventorKeith W. Goossen

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Abstract

A tunable monolithic integrated photodetector (10) detects a selected wavelength of incident light within a wavelength range. The photodetector comprises a multiple quantum well (MQW) filter means for receiving and filtering the incident light, and an MQW detector means for receiving light from the MQW filter means and for detecting the selected wavelength. A fixed voltage bias V.sub..DELTA. is disposed between the filter means and the detector means for causing the filter means to absorb light wavelengths around the selected wavelength to thereby enhance the detectability of the selected wavelength. Further, a variable voltage bias V.sub.P is selectively and proportionally imposed on both the filter means and the detector means for permitting tuning of the photodetector. A fixed filter may also be employed for filtering the incident light so that light wavelengths which are outside the range of the photodetector are eliminated. Finally, a plurality of the photodetectors may be arranged in a two dimensional array for image processing.

Claims23

Dependent claims

A tunable monolithic integrated photodetector for determining a wavelength of incident light, comprising:

a filter means for receiving and filtering the incident light, said filter means comprising an intrinsic first multiple quantum well material having first and second filter surfaces;
a detector means for receiving light from said filter means and for exhibiting a peak photocurrent when the incident light exhibits a selected wavelength, said detector means comprising an intrinsic second multiple quantum well material having first and second detector surfaces;
a variable voltage source with variable voltage positive and negative terminals, said variable voltage negative terminal being connected to said second filter surface and to said first detectors surface, said variable voltage source being adapted to apply a variable bias between said variable voltage positive and negative terminals, said variable bias being capable of adjustment for tuning and specifying the selected wavelength;
and
a fixed voltage source with fixed voltage positive and negative terminals, said fixed voltage negative terminal being connected to said first filter surface, said fixed voltage positive terminal being connected to said variable voltage positive terminal, said fixed and variable voltage sources and said filter means together forming a series circuit loop for permitting substantially resistance free current flow through said filter means and said fixed and variable voltage sources, said fixed voltage source applying a fixed bias between said fixed voltage positive and negative terminals for causing said filter means to absorb light wavelengths shorter than the selected wavelength to thereby enhance the detectability of the peak photocurrent in said detector means,
whereby the wavelength of the incident light is identified by monitoring said detector means for the peak photocurrent while said variable bias is adjusted.

3 more elements

A tunable monolithic integrated photodetector for determining a wavelength of incident light, comprising:

a filter means for receiving and filtering the incident light, said filter means comprising an intrinsic first multiple quantum well material;
a detector means for receiving light from said filter means and for exhibiting a peak photocurrent when the incident light exhibits a selected wavelength, said detector means comprising an intrinsic second multiple quantum well material;
a detector voltage source for applying a detector bias across said detector means, said detector bias capable of adjustment for tuning and specifying the selected wavelength;
and
a filter voltage source for applying a filter bias across said filter means, said filter voltage source being connected in series with said filter means for permitting current flow through said filter means and said bias means without resistance, said filter bias for causing said filter means to absorb light wavelengths shorter than the selected wavelength to thereby enhance the detectability of the peak photocurrent in said detector means,
whereby the wavelength of the incident light is identified by detecting the peak photocurrent through said detector means during the adjustment of said detector bias.

3 more elements

Dependencies are inferred from the claim text.