Question

A silicon wafer is used to attenuate the intensity from a laser emitting at a wavelength of 0.8 µm. If the laser output power is 100 mW what is the wafer thickness required to attenuate the power to 1 mW?

Answer 1

`t =4.605 *10^(-3)`

Step-by-step explanation:

given data:

wavelength of emission =
`0.8 \mu m`

output power = 100 mW

We can deduce value of obsorption coefficient from the graph obsorption coefficient vs wavelength

for wavelength
`0.8 \mu m` the obsorption coefficient value is 10^{3}

intensity can be expressed as a function of thickness as following:

`I(t) = I_(O) *e^(-\lambda *t)`

putting all value to get thickness

`1*10^(-3) =100*10^(-3)e^{-10^(3)*t}`

`0.01 = e^{10^(3)t}`

`t =4.605 *10^(-3)`