Optical field inscription for dark pulse generation.

Area of Science:

• Optics and Photonics
• Nonlinear Optics

Background:

• Dark pulses are valuable for optical communication and sensing due to their robustness.
• Current methods for generating dark pulses, such as nonlinear Schrödinger equation (NLSE)-driven dark solitons and domain-wall dark pulses, have limitations including reliance on dispersive media or confinement to fiber lasers.

Purpose of the Study:

• To introduce a novel optical field inscription technique for generating dark pulses in the negative group velocity dispersion (GVD) regime.
• To address the limitations of existing dark pulse generation methods by providing a dispersion-independent approach.

Main Methods:

• A mode-locked bright soliton from a 1550-nm fiber laser is dechirped to a transform-limited pulse.
• A temporal hyperbolic tangent-like profile with a π-phase jump is inscribed onto the seed pulse using online optical field modulation.
• The inscribed pulse is then expanded into a dispersion-scaled dark pulse structure.

Main Results:

• The generated dark pulse structures exhibit the characteristic π-phase jump and intensity dip of dark solitons.
• The ns-scale structure of the dark pulses is determined by linear stretching, independent of the balance between dispersion and nonlinearity.
• Experimental results align well with theoretical predictions.
• Dynamic generation of different dark pulse patterns (black and gray) is achieved by adjusting inscription widths.

Conclusions:

• This work presents a dynamic, dispersion-independent method for programmable dark pulse generation.
• The technique overcomes key limitations of existing approaches, offering a new route for advanced optical signal generation.
• Potential applications include reconfigurable optical communication and sensing systems.