Method for phase-based photonic computing

1. A method for optical computation comprising:

throughout a time period, controlling a filter bank based on a plurality of weights, comprising:

based on a first weight of the plurality, determining a first control signal;

based on a second weight of the plurality, determining a second control signal, wherein the second weight is different from the first weight;

providing the first control signal to a first optical filter of the filter bank, wherein the first optical filter is associated with a first optical characteristic; and

providing the second control signal to a second optical filter of the filter bank, wherein the second optical filter is associated with a second optical characteristic different from the first optical characteristic;

during the time period, receiving a first optical input signal at a first waveguide of the filter bank, wherein the first optical input signal comprises:

a first portion having the first optical characteristic; and

a second portion having the second optical characteristic;

during the time period, substantially concurrent with receiving the first optical input signal, receiving a second optical input signal at a second waveguide of the filter bank, wherein the second optical input signal comprises:

a third portion having the first optical characteristic; and

a fourth portion having the second optical characteristic; and

during the time period, in response to receiving the first and second optical input signals:

at the first optical filter, based on the first control signal, phase shifting the first portion by a first phase shift amount;

at the second optical filter, based on the second control signal, phase shifting the second portion by a second phase shift amount, different from the first phase shift amount;

after phase shifting the first and second portions, generating an optical output signal, comprising coupling the first optical input signal and the second optical input signal; and

outputting the optical output signal.

2. The method of claim 1 , further comprising, at an optical splitter, during the time period:

receiving a combined optical input signal;

splitting the combined optical input signal into the first and second optical input signals;

providing the first optical input signal to the first waveguide; and

providing the second optical input signal to the second waveguide.

3. The method of claim 2 , wherein:

the optical splitter further splits the combined optical input signal into a third optical input signal and a fourth optical input signal;

the third optical input signal comprises a fifth portion having the first optical characteristic and a sixth portion having the second optical characteristic; and

the fourth optical input signal comprises a seventh portion having the first optical characteristic and an eighth portion having the second optical characteristic;

the method further comprising:

throughout the time period, controlling a second filter bank based on a second plurality of weights, comprising:

based on a third weight of the second plurality, determining a third control signal, wherein the third weight is different from the first and second weights;

based on a fourth weight of the second plurality, determining a fourth control signal, wherein the fourth weight is different from the first, second, and third weights;

providing the third control signal to a third optical filter of the second filter bank, wherein the third optical filter is associated with the first optical characteristic; and

providing the fourth control signal to a fourth optical filter of the second filter bank, wherein the fourth optical filter is associated with the second optical characteristic;

during the time period, substantially concurrent with receiving the first and second optical input signals:

at a third waveguide of the second filter bank, receiving the third optical input signal from the optical splitter; and

at a fourth waveguide of the second filter bank, receiving the fourth optical input signal from the optical splitter;

during the time period, in response to receiving the third and fourth optical input signals:

at the third optical filter, based on the third control signal, phase shifting the fifth portion by a third phase shift amount different from the first and second phase shift amounts;

at the fourth optical filter, based on the fourth control signal, phase shifting the sixth portion by a fourth phase shift amount different from the first, second, and third phase shift amounts;

after phase shifting the fifth and sixth portions, generating a second optical output signal, comprising coupling the third optical input signal and the fourth optical input signal; and

outputting the second optical output signal.

4. The method of claim 3 , further comprising:

at a first optical detector, sampling a first amplitude of the optical output signal; and

at a second optical detector, sampling a second amplitude of the second optical output signal.

5. The method of claim 1 , wherein a first intensity ratio, defined by a first portion intensity divided by a third portion intensity, is substantially equal to a second intensity ratio, defined by a second portion intensity divided by a fourth portion intensity.

6. The method of claim 5 , wherein the first optical input signal is substantially identical to the second optical input signal.

7. The method of claim 1 , wherein:

the first optical input signal further comprises a fifth portion having a third optical characteristic different from the first and second optical characteristics;

the second optical input signal further comprises a sixth portion having the third optical characteristic;

the filter bank further comprises a third optical filter associated with the third optical characteristic;

controlling the filter bank based on the plurality of weight further comprises:

based on a third weight of the plurality, determining a third control signal; and

providing the third control signal to the third optical filter; and

the method further comprises, during the time period, in response to receiving the first and second optical input signals, before generating the optical output signal: at the third optical filter, based on the third control signal, phase shifting the fifth portion by a third phase shift amount.

8. The method of claim 1 , wherein:

the first optical input signal further comprises a fifth portion having a third optical characteristic different from the first and second optical characteristics;

the second optical input signal further comprises a sixth portion having the third optical characteristic;

the filter bank further comprises a third optical filter associated with the third optical characteristic;

controlling the filter bank based on the plurality of weight further comprises:

based on a third weight of the plurality, determining a third control signal; and

providing the third control signal to the third optical filter; and

the method further comprises, during the time period, in response to receiving the first and second optical input signals, before generating the optical output signal: at the third optical filter, based on the third control signal, phase shifting the sixth portion by a third phase shift amount.

9. The method of claim 1 , further comprising:

throughout a second time period after the time period, controlling the filter bank based on a second plurality of weights, comprising:

based on a third weight of the second plurality, determining a third control signal, wherein the third weight is different from the first and second weights;

based on a fourth weight of the second plurality, determining a fourth control signal, wherein the fourth weight is different from the first, second, and third weights;

providing the third control signal to the first optical filter; and

providing the fourth control signal to the second optical filter;

during the second time period, receiving a third optical input signal at the input waveguide, wherein the third optical input comprises:

a fifth portion having the first optical characteristic; and

a sixth portion having the second optical characteristic;

during the second time period, substantially concurrent with receiving the third optical input signal, receiving a fourth optical input signal at the second waveguide, wherein the fourth optical input signal comprises:

a seventh portion having the first optical characteristic; and

an eighth portion having the second optical characteristic; and

during the second time period, in response to receiving the third and fourth optical input signals:

at the first optical filter, based on the third control signal, phase shifting the fifth portion by a third phase shift amount different from the first and second phase shift amounts;

at the second optical filter, based on the fourth control signal, phase shifting the sixth portion by a fourth phase shift amount different from the first, second, and third phase shift amounts;

after phase shifting the fifth and sixth portions, generating a second optical output signal, comprising coupling the third optical input signal and the fourth optical input signal; and

outputting the second optical output signal.

10. The method of claim 1 , wherein:

the first optical characteristic is a first optical wavelength;

the second optical characteristic is a second optical wavelength;

the first optical filter comprises a first wavelength-selective filter; and

the second optical filter comprises a second wavelength-selective filter.

11. The method of claim 10 , wherein:

the first wavelength-selective filter comprises a first microresonator;

the second wavelength-selective filter comprises a second microresonator;

providing the first control signal to the first optical filter alters a first resonance wavelength of the first microresonator; and

providing the second control signal to second first optical filter alters a second resonance wavelength of the second microresonator.

12. The method of claim 1 , wherein:

the first portion has a first input intensity x 1 ;

the second portion has a second input intensity x 2 ;

the optical output signal comprises:

a first output portion having the first optical characteristic, the first output portion having a first output intensity y 1 ; and

a second output portion having the second optical characteristic, the second output portion having a second output intensity y 2 ; and

x 1 w 1 /y 1 is substantially equal to x 2 w 2 /y 2 , wherein w 1 represents the first weight and w 2 represents the second weight.