Generation of triangular waveforms based on a microwave photonic filter with negative coefficient.

Area of Science:

• Photonics
• Electrical Engineering
• Signal Processing

Background:

• Triangular waveforms are essential in various applications.
• Generating pure triangular waveforms with suppressed even-order harmonics is challenging.
• Existing methods often require complex components like broadband phase shifters.

Purpose of the Study:

• To propose and verify a novel approach for generating full-duty-cycle triangular waveforms.
• To suppress undesired even-order harmonics using a microwave photonic filter (MPF).
• To explore two methods for triangular waveform generation: fundamental frequency and frequency doubling.

Main Methods:

• Utilizing a microwave photonic filter (MPF) with a negative coefficient and periodic transmission response.
• Employing a Mach-Zehnder modulator (MZM) biased at quadrature point for fundamental frequency generation.
• Biasing the MZM at maximum or minimum transmission for frequency doubling.
• Theoretical analysis and experimental verification of the proposed methods.

Main Results:

• The MPF effectively suppresses even-order harmonics, enabling triangular waveform generation.
• Fundamental frequency generation requires a broadband 90° microwave phase shifter.
• Frequency doubling generation eliminates the need for a phase shifter but is more power-consuming.
• Both methods were theoretically analyzed and experimentally validated.

Conclusions:

• The proposed MPF-based approach offers an effective solution for generating triangular waveforms.
• The frequency doubling method presents a more promising, albeit power-intensive, alternative.
• This work contributes to advancements in photonic signal generation and processing.