Reconfigurable microwave photonic filter based on a quantum dash mode-locked laser

Area of Science:

• Photonics
• Optical Engineering
• Laser Technology

Background:

• Microwave photonic (MWP) filters are crucial for signal processing.
• Reconfigurability and programmability are key challenges in MWP filter design.
• Quantum dash mode-locked lasers (QDash-MLLs) offer potential for generating optical frequency combs (OFCs).

Purpose of the Study:

• To demonstrate a reconfigurable MWP filter.
• To utilize a QDash-MLL for generating an OFC to program MWP filter responses.
• To explore the programmability and performance of such a system.

Main Methods:

• A QDash-MLL was employed to generate an optical frequency comb with approximately 50 comb lines and a 25 GHz free spectral range.
• The OFC spectrum was tailored to program various MWP filter responses.
• Filter characteristics such as bandwidth, out-of-band rejection, and central frequency tuning were measured.

Main Results:

• Reconfigurable MWP filter responses including Gaussian, sinc, flat-top, and multiple peaks were successfully implemented.
• A minimum 3 dB bandwidth of approximately 100 MHz was achieved for a sinc-shaped filter.
• A maximum out-of-band rejection of up to 30 dB was demonstrated with Gaussian apodization.
• Tuning of the central frequency was also demonstrated.

Conclusions:

• QDash-MLLs are a viable and promising source for generating OFCs suitable for integrated and reconfigurable MWP filters.
• The ability to tailor OFC spectra allows for flexible programming of MWP filter responses.
• The demonstrated performance metrics indicate the potential for practical applications in advanced signal processing.