Patent ID: 7439481

Claim:
An in-line monitoring apparatus to monitor input power of an optical signal received by an optical signal detector across temperature variations, said in-line monitoring apparatus comprising: an avalanche photodiode (“APD”) configured to receive said optical signal; an input configured to provide a bias for said APD; a power monitoring stage coupled to said input in parallel with said APD and further configured to generate a measurement signal in-situ; wherein said power monitoring stage comprises two or more power monitoring stages to establish an extended input power range over which said power monitoring stage can measure said input power, each of said two or more power monitoring stages being configured to measure input power values within a corresponding portion of said extended input power range; wherein two or more power monitoring stages further comprises a first power monitoring stage configured to detect a low-powered optical signal as said input power and a second power monitoring stage configured to provide a linear range of input optical power levels; a temperature compensator configured to adjust an operational parameter of said APD as a function of temperature and said measurement signal; and wherein said measurement signal is representative of said input power.