Method for non-binary difference computation with light

An optical numerical computation method, comprising:

• obtaining operands, including a first operand having a first respective value and a first respective sign, and including a second operand having a second respective value and a second respective sign;
• providing light sources to emit light, including a first light source to emit first light and a second light source to emit second light;
• modulating the first light source to output the first light with a first amplitude proportional to the first respective value at a first wavelength λ1;
• modulating the second light source to output the second light with a second amplitude proportional to the second respective value, including:
• when the first respective sign matches the second respective sign, outputting the second light at the first wavelength λ1, and
• when the first respective sign does not match the second respective sign, outputting the second light at a second wavelength λ2;
• providing the light inside a light collection cavity that has an inner surface devoid of openings that admit light from other than the light sources;
• providing light sensors adapted to sense the light in the light collection cavity, including a first light sensor and a second light sensor, wherein:
• the first light sensor is adapted to sense the light having the first wavelength λ1 and to have a respective resistance that decreases as sensed light increases, and
• the second light sensor is adapted to sense the light having the second wavelength λ2 and to have a respective resistance that increases as sensed light increases, the second light sensor being coupled in series with the first light sensor;
• sensing the light, including the first light and the second light, in the light collection cavity, using the light sensors, to obtain a resultant value;
• and
• outputting the resultant value as a calculation result of combining the operands.