Integrated High-Resolution Optical Spectrum Analyzer With Broad Operational Bandwidth

Precise optical spectrum analysis with high resolution by an economical and reliable device is of much interest in optical science and technology. In this work, we propose a silicon-photonic integrated optical spectrum analyzer comprised of two cascaded filters. A first ring resonator stage selects multiple ultra-narrow spectral bands of equal spacing. The set of bands may be scanned across the spectrum of interest through thermal tuning. A second filter stage separates the multiple sampled bands into different output ports. The free spectral ranges of the two stages are matched. The spectrum is reconstructed using simple, low bandwidth photodiodes. In a proof of concept experiment, the proposed integrated optical spectrum analyzer shows a wide operational range with 128MHz resolution.