Photodetector
AssigneeNippon Telegraph and Telephone Corporation
InventorKotaro Takeda
Life of this patent
Estimating the term…
Abstract
A problem to be solved is to prevent deterioration of a signal-to-noise ratio. A photodetector according to the present invention is a germanium photodetector (Ge PD) that uses germanium or a germanium compound in a light absorption layer, the photodetector including a resistor connected in series with a cathode or an anode of the Ge PD; and a capacitor connected at one end to a connection point between the resistor and a cathode or anode of the Ge PD and grounded at another end, another connection point of the resistor being connected to a bias power supply, wherein to withstand maximum operating optical input power, the value of the resistor is determined such that electric power applied to the Ge PD will be lower than a breakdown threshold.
Claims8
A photodetector comprising:
- a photodiode including a light absorption layer that contains germanium or a germanium compound;
- a resistor connected in series with a cathode or an anode of the photodiode;
- and
- a capacitor connected to a connection point between the resistor and the cathode or the anode, another connection point of the resistor being connected to a bias power supply, wherein
- the resistor has a value between resistance values RAM and RM, both inclusive, determined by
- [
- Math
- .
- 1
- ]
- RAM
- =
- (
- E
-
- l
- -
- Pbreak
- M
-
- Pphoto_AM
- )
-
- (
- 1
- M
-
- Pphoto_AM
- )
- [
- Math
- .
- 2
- ]
- RM
- =
- (
- El
- -
- V_M
- )
-
- (
- 1
- M
-
- Photo_M
- )
- where R is a resistance value of the resistor, E is an electric field applied to a depletion layer of the photodiode, l is a depletion layer thickness of the photodiode, Pbreak is breakdown power of the photodiode, M is sensitivity of the photodiode, PphotoAM is maximum rated optical input power to the photodiode, PphotoM is maximum operating optical input power to the photodiode, and V_M is a value of voltage applied to the photodiode when maximum operating optical input power is input to the photodiode, and
- the electric field E×the depletion layer thickness l has a value between 7 V and 12 V.
A photodetector comprising:
- two or more photodiodes each including a light absorption layer that contains germanium or a germanium compound, all cathodes or all anodes being interconnected;
- a resistor connected in series with the cathodes or the anodes;
- and
- a capacitor connected to a connection point between the resistor and the cathodes or the anodes, another connection point of the resistor being connected to a bias power supply, wherein
- the resistor has a value between resistance values RAM and RM, both inclusive, determined by
- [
- Math
- .
- 3
- ]
- RAM
- =
- (
- El
- -
- Pbreak
- ∑
- n
- =
- 1
- n
-
- M
- n
-
- PphotoAM_n
- )
-
- (
- 1
- ∑
- n
- =
- 1
- n
-
- M
- n
-
- PphotoAM_n
- )
- [
- Math
- .
- 4
- ]
- RM
- =
- (
- El
- -
- V_M
- )
-
- (
- 1
- ∑
- n
- =
- 1
- n
-
- M
- n
-
- PphotoM_n
- )
- where R is a resistance value of the resistor, E is an electric field applied to a depletion layer of each of the photodiodes, l is a depletion layer thickness of each of the photodiodes, Pbreak is breakdown power of each of the photodiodes, V_M is a value of voltage applied to each of the photodiodes when maximum operating optical input power is input to the photodiodes, M1 is sensitivity of a first of the photodiodes, M2 is sensitivity of a second of the photodiodes, as many sensitivities Mn as the number n of photodiodes being defined, PphotoAM_1 is maximum rated optical input power to the first photodiode and PphotoAM_2 is maximum rated optical input power to the second photodiode, as many maximum rated optical input powers PphotoAM_n as the number n of photodiodes being defined, and PphotoM_1 is maximum operating optical input power to the first photodiode and PphotoM_2 is maximum operating optical input power to the second photodiode, as many maximum operating optical input powers PphotoAM_n as the number n of photodiodes being defined, and
- the electric field E×the depletion layer thickness l has a value between 7 V and 12 V.
Dependencies are inferred from the claim text.