Optical Adder Using 2 Lasers & Selectable Intensities

[010101]

If we use 2 lasers with selectable light intensities as input, with each level of intensity corresponding to decimal number.
Like
level 0 intensity - decimal 0 (MIN)
level 1 intensity - decimal 1
level 2 intensity - decimal 2
...
level 9 intensity - decimal 9 (MAX)

and directly shine both of them over photo detector, there intensities will add up to produce sum. thus we can measure the current from photo detector to see what number is it.
we can also use laser of other frequencies to implement parallelism.

I know this solution is simple but I don't get it why won't it work either.

 

[mfb]

The photodetector is not optical, you have to extract an electronic signal from it.

 

[010101]

So they also want detector to be fully optical, that means output to be pure light and that means all optical memory with read and write capabilities.
That thing would be difficult to make.

 

[mfb]

Who is "they"? Fully optical elements would allow some things to be faster in some specialized systems.

 

[010101]

they means the scientists. One question though what is the bone of contention in realizing full optical computing ?
is it the material which is lacking to manipulate light with light. from what I have googled most say it is the material, while these things (optical transistor, the read/write capable memory, the all optical amplifiers, optical buffers) have already been demonstrated.

 

[mfb]

All those things rely on manipulating light with light in some way.