Spectrally Equalized Frequency Comb Generation in Multistage Parametric Mixer With Nonlinear Pulse Shaping

• Published in: Journal of lightwave technology 2014-02, Vol.32 (4), p.840-846
• Main Authors: Ataie, Vahid, Myslivets, Evgeny, Kuo, Bill P-P, Alic, Nikola, Radic, Stojan
• Format: Article
• Language: English
• Subjects: Chirp; Dispersion; Exact sciences and technology; Filters, zone plates, and polarizers; Frequency modulation; Fundamental areas of phenomenology (including applications); Mixers; Nonlinear optics; nonlinear pulse shaping; OFDM; Optical elements, devices, and systems; optical frequency comb; Optics; Parametric process; Phase modulation; Physics
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2013.2287852

A novel approach to improve the flatness of wide-band parametric frequency combs is presented. The method relies on nonlinear pulse shaping prior to parametric mixing in a comb-generating device. The parametric comb is generated in a cavity-less multistage shock-wave mixer, using continuous-wave (CW) laser as comb seed. The pulse shaping is accomplished in a regenerative stage incorporating nonlinear optical/amplifying loop mirror (NOLM/NALM) and provides near-ideal seeds for spectrally equalized frequency comb generation in the output mixing stage. The new technique was implemented separately on two comb generators with a coarse (100 GHz) and dense (10 GHz) tone spacing. A 4 dB flatness over 100 nm is achieved with wide-pitched comb, while the fine-pitched device yielded 1500 tones and possessed sub-2 dB spectral flatness over 120 nm bandwidth.