Mach-Zehnder-modulator-based Flat Comb Generator Research Articles

High precision frequency measurement of terahertz waves using optical combs from a Mach-Zehnder-modulator-based flat comb generator.

Using a frequency-tunable optical comb generated from a Mach-Zehnder-modulator-based flat comb generator (MZ-FCG) and a nonlinear optical fiber, we demonstrated a frequency measurement of continuous terahertz wave sources with the frequency of 0.1 and 0.6THz by an electro-optic sampling method. We clearly observed beat signals between the terahertz source and the optical two-tone extracted from the optical comb, allowing us to determine the absolute frequency. Owing to the wide comb spacing of the MZ-FCG, this method has a high potential for the high-speed measurement of the frequency of terahertz wave sources.

Ultrashort optical pulse source using Mach–Zehnder-modulator-based flat comb generator

We reported ultrashort pulse generation using a Mach–Zehnder-modulator-based flat comb generator (MZ-FCG) and a dispersion-flattened dispersion-decreasing fiber (DF-DDF). Our source has high stability, low jitter, and independent control of the repetition rate and center wavelength. 80 fs-order ultrashort pulse generation was demonstrated. The phase noise of the ultrashort pulse train is determined by that of the microwave signal driving the MZ-FCG, which was -110 dBc/Hz at the offset frequency of 100 kHz. The rms timing jitter of the femtosecond pulses was 80 fs, and the frequency stability evaluated with Allan deviation was in the order of 10−13.

Broadband wavelength-tunable ultrashort pulse source using a Mach–Zehnder modulator and dispersion-flattened dispersion-decreasing fiber

The broadband wavelength tunability of femtosecond pulse generation using a Mach-Zehnder-modulator-based flat-comb generator (MZ-FCG) and a dispersion-flattened dispersion-decreasing fiber (DF-DDF) was demonstrated. Near-Fourier-transform-limit picosecond pulses generated from the MZ-FCG were compressed into femtosecond pulses by adiabatic soliton compression. By tuning the wavelength of the input cw light, 200 fs, 10 GHz pulses were generated in the wavelength range of 1,535 to 1,570 nm. Such wide-range wavelength tunability was realized by both the independence of a comb-flattening condition from the inputted wavelength and the dispersion flatness of the DF-DDF.

Widely repetition-tunable 200 fs pulse source using a Mach–Zehnder-modulator-based flat comb generator and dispersion-flattened dispersion-decreasing fiber

By combining a Mach-Zehnder-modulator-based flat comb generator (MZ-FCG) with a dispersion-flattened dispersion-decreasing fiber, femtosecond pulses have been generated from a cw light. Near-Fourier-transform-limit picosecond pulses generated from the MZ-FCG were compressed into femtosecond order by pulse compression. Our system enables flexible tuning of the repetition rate and pulse width, because those depend on the driving signal of the MZ-FCG. Pulse trains of 200 fs width were continuously and stably generated without mode hopping, with a repetition rate range from 5 to 17 GHz. Our system consists of a modulator and compression fiber; thus, the configuration is simpler and more stable.