Broadband dynamic spectrum characterization based on gating-assisted electro-optic time lens

Abstract

A broadband real-time optical spectrum characterization technique is proposed based on a gating-assisted electro-optic time lens. Operating at the repetition rate of 10-MHz, a 10-dB spectral measurement range of more than 70-nm is achieved with a resolution of up to 42.5-pm in the near-infrared regime. To demonstrate its performance in applications, real-time spectral observation of broadband wavelength sweeping of a Fourier domain mode-locked laser and a 32.4-GHz optical frequency comb is presented. Furthermore, a detailed comparison between dispersive Fourier transform and the time lens based spectral analysis technique for frequency comb measurements is made from both simulation and experiment. With its broadband performance, this technique can provide widespread applications requiring real-time spectral analysis.

The authors acknowledge the Research Grants Council of the Hong Kong Special Administrative Region, China (Project Nos. HKU 17205215, CityU T42-103/16-N, HKU C7047-16G, EHKU701/17, and HKU 17209018) and National Natural Science Foundation of China (N_HKU712/16).