Fast-fourier-transformation de-convolutions for a fabry-perot filter based OSA: demonstration of 15.0 dB increase of optical-rejection ratio at /spl I.chemo/25.0 GHz from peak

An optical spectrum analyzer (OSA) based on a tunable Fabry-Perot filter (TFPF) has been implemented. The TFPF has free spectrum range (FSR) of about 180 nm, finesse of about 7200, and 3-dB bandwidth of less than 80.0 pm. Its optical rejection ratio (ORR) at ±25.0 GHz away from its main transmission peak is about 24.5 dB. We demonstrated that Fast-Fourier-Transformation (FFT) de-convolutions can be employed to enhance its ORR by more than 15 dB at ±25.0 GHz. This is the first time that FFT de-convolutions have been demonstrated to greatly enhance the ORR of a TFPF for OSA applications (with one patent pending).