Voltage-tunable photodetector

Claim 1

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.

Claim 24

A method of identifying a wavelength of light with a monolithic integrated structure having an intrinsic first multiple quantum well layer for receiving incident light and an intrinsic second multiple quantum well layer for receiving light from said first multiple quantum well layer, the second multiple quantum well layer for exhibiting a peak photocurrent when the incident light exhibits a selected wavelength, the method comprising the steps of: applying first and second voltage biases across said first and second multiple quantum well layers, respectively; adjusting said first voltage bias to cause said second multiple quantum well layer to absorb light wavelengths shorter than the selected wavelength thereby to enhance the detectability of the peak photocurrent; varying said second voltage bias to tune and specify the selected wavelength; and permitting current flow through said first multiple quantum well and around a series circuit loop which is free of resistance elements.

Claim 25

A method of identifying a wavelength of light with a monolithic integrated structure having an intrinsic first multiple quantum well layer for receiving incident light and an intrinsic second multiple quantum well layer for receiving light from said first multiple quantum well layer, the second multiple quantum well layer for exhibiting a peak photocurrent when the incident light exhibits a selected wavelength, the method comprising the steps of: applying first and second voltage biases across said first and second multiple quantum well layers, respectively; adjusting said first voltage bias to cause said second multiple quantum well layer to absorb light wavelengths shorter than the selected wavelength thereby to enhance the detectability of the peak photocurrent; varying said second voltage bias to tune and specify the selected wavelength; and permitting current flow through said first multiple quantum well and around a series circuit loop which is free of resistance elements.