Spectral responsivity uncertainty of silicon photodiodes due to calibration spectral bandwidth

A systematic study on the uncertainty in spectral responsivity of silicon p hotodiodes due to the calibration spectral bandwidth is presented. Two of t he most common types of silicon photodiodes in the field of optical power m easurements have been used in this work: one with thickness of about 100 nm Of SiO2 and the other with thickness about 27 nm Of SiO2. It is shown that the spectral responsivity error will be negligible (less than or equal to5 x 10(-4)) using a spectral bandwidth up to 20 nm in the calibration if the effective wavelength of the spectral transfer function, including the dist ribution of the radiation source, is calculated and the measured responsivi ty is assigned to that effective wavelength. In other cases, the error depe nds not only on the extent of the interval isolated by the spectral analysi s system but also on the shape of the spectral isolation function.