Ultrahigh‐resolution coherent optical spectrum analysis based on electrical frequency sweeping with a doubled measurement range

Abstract

Based on electrical frequency sweeping, an ultrahigh-resolution coherent optical spectrum analyser with a doubled measurement range is proposed and experimentally demonstrated. In the scheme, a frequency-swept electrical signal is converted to the optical domain. By selecting one of the second-order sidebands of the generated optical signal, a wavelength-swept signal with a frequency range that is twice the bandwidths of the electro-optic and RF components is generated. With the wavelength-swept signal, high-resolution optical spectrum analysis with a doubled measurement range is implemented. In a proof-of-concept experiment, the spectrum of a multi-tone optical signal with a bandwidth of 20 GHz is measured with a resolution of 1.5 MHz by employing 10 GHz components.