Low power, chip-based stimulated Brillouin scattering microwave photonic filter with ultrahigh selectivity (1412.4236v1)

Abstract: Highly selective and reconfigurable microwave filters are of great importance in radio-frequency signal processing. Microwave photonic (MWP) filters are of particular interest, as they offer flexible reconfiguration and an order of magnitude higher frequency tuning range than electronic filters. However, all MWP filters to date have been limited by trade-offs between key parameters such as tuning range, resolution, and suppression. This problem is exacerbated in the case of integrated MWP filters, blocking the path to compact, high performance filters. Here we show the first chip-based MWP band-stop filter with ultra-high suppression, high resolution in the MHz range, and 0-30 GHz frequency tuning. This record performance was achieved using an ultra-low Brillouin gain from a compact photonic chip and a novel approach of optical resonance-assisted RF signal cancellation. The results point to new ways of creating energy-efficient and reconfigurable integrated MWP signal processors for wireless communications and defence applications.

• The paper demonstrates a chip-based SBS microwave photonic filter achieving >55 dB suppression and 32–88 MHz resolution with only 8–12 mW pump power.
• It utilizes a compact chalcogenide glass waveguide to enable frequency tuning from 0 to 30 GHz without compromising performance.
• The study advances energy-efficient, reconfigurable RF filtering for high-speed wireless communications and next-generation radar systems.

Overview of Chip-Based SBS Microwave Photonic Filters with Ultra-High Selectivity

The presented paper discusses the realization of a chip-based stimulated Brillouin scattering (SBS) microwave photonic filter offering unprecedented selectivity and low-power requirements. This research addresses significant challenges in radio-frequency (RF) filtering, specifically focusing on integrated microwave photonic (IMWP) filters. These are notable for their reconfiguration abilities and broad tuning ranges, but have historically suffered from poor resolution and high power consumption.

Key Technological Contributions

1. Ultra-High Suppression and Resolution: The authors introduce a band-stop filter demonstrated on a compact chalcogenide glass waveguide. This filter exhibits stop-band suppression exceeding 55 dB, coupled with high resolution in the range of 32-88 MHz. The demonstrated performance stands out particularly due to the low SBS gain (1-4 dB) and minimal pump power (8-12 mW) required.
2. Wide Frequency Tuning: The filter supports frequency tuning from 0 to 30 GHz, a feature that enhances its utility for dynamic RF applications. This is achieved without compromising the selectivity or resolution, making the filter a potent tool for spectral efficiency tasks.
3. Energy Efficiency and Reconfiguration: The authors showcase a method utilizing optical resonance-assisted RF signal cancellation, improving energy efficiency by redistributing optical power to reduce insertion loss significantly. This approach is critical for energy-constrained environments and supports dynamic reconfiguration.

Experimental Results

In experimental setups, the novel SBS-filter achieved a massive 43-fold reduction in required pump power compared to traditional methods, illustrating a peak suppression of 55 dB with only 4 dB of SBS gain. This is a substantial improvement over existing conventional filters, which required much higher power for moderate levels of suppression. The ability to maintain high suppression levels with reduced power use positions this technology favorably for integrated photonic applications.

Practical and Theoretical Implications

The practical implications of this research are profound in domains such as high data rate wireless communications and next-generation radar systems, where both spectral efficiency and energy consumption are crucial. Theoretically, this paper advances the exploration of SBS in a nanophotonic context, which could lead to further miniaturization and integration of photonic technologies on silicon chips.

Future Prospects

The findings suggest avenues for further research and development, including enhancing the integration of RF signal processing on compact, monolithic chips. Future work could explore the potential improvements in photonic link efficiency and insertion loss mitigation through advanced fabrication techniques and material innovations.

In summary, this paper opens new opportunities in the design of integrated microwave photonic filters, offering a compelling combination of high performance with reduced power demands. Such advancements are critical for addressing the growing needs of modern RF system architectures.