Optical Nyquist pulse generation using a time lens with spectral slicing.

Area of Science:

• Photonics
• Optical Communications
• Signal Processing

Background:

• Nyquist pulses are crucial for high-speed optical communication systems.
• Generating chirp-free Nyquist pulses with precise control over spectral shape and frequency spacing remains a challenge.

Purpose of the Study:

• To propose and experimentally demonstrate a novel optical Nyquist pulse generation technique.
• To achieve nearly chirp-free Nyquist pulses with a 10-GHz repetition rate.
• To explore the flexibility of the proposed method for C-band and dual-wavelength operation.

Main Methods:

• Utilizing a time lens system with cascaded phase and amplitude modulators.
• Incorporating group velocity dispersion (GVD) to generate an ultraflat optical frequency comb (OFC).
• Employing a tunable rectangular-shaped optical band-pass filter (OBPF) for spectral shaping and standard single-mode fiber (SSMF) for chirp compensation.

Main Results:

• Experimental demonstration of a nearly chirp-free 10-GHz, 8.1-ps Nyquist pulse generator.
• Generation of an 11-tone ultraflat optical frequency comb with 10-GHz spacing and <0.9 dB power variation.
• Successful generation of nearly chirp-free Nyquist pulses across the C-band by tuning the continuous wave (CW) light wavelength.
• Demonstration of simultaneous dual-wavelength pulse generation.

Conclusions:

• The proposed time lens-based method offers an effective approach for generating high-quality Nyquist pulses.
• The technique provides flexibility in terms of operating wavelength (C-band) and enables dual-wavelength generation.
• This advancement has significant implications for future high-capacity optical communication systems.