Wideband‐Tunable on‐Chip Microwave Photonic Filter with Ultrahigh‐Q U‐Bend‐Mach–Zehnder‐Interferometer‐Coupled Microring Resonators

Abstract

Microwave photonic filters are a key fundamental subsystem in microwave photonics. A wideband‐tunable on‐chip microwave photonic filter (MPF), which monolithically integrates a dual‐drive Mach‐Zehnder modulator (DDMZM), is proposed with ultrahigh‐Q Mach–Zehnder‐interferometer (MZI)‐coupled microring resonators (MRRs) in cascade and a high‐speed photodetector (PD). It is the first time an MPF has been developed by introducing U‐bend‐MZI‐coupled MRRs whose resonance wavelength and 3 dB bandwidth are tunable. In particular, the ultrahigh‐Q U‐bend‐MZI‐coupled MRRs are realized with ultralow loss broadened silicon waveguides based on a modified Euler curve. For the fabricated U‐bend‐MZI‐coupled MRRs, which have an effective radius of 29 µm, the Q‐factor is as high as 1.3 × 106, while the free spectral range (FSR) is as large as 113 GHz. Furthermore, the introduction of two cascaded U‐bend‐MZI‐coupled MRRs enables the MPF to have flat‐top bandstop (or bandpass) responses with a high extinction ratio (ER) of 20–35 dB as well as a tunable 3 dB bandwidth of 0.15–3 GHz. Meanwhile, the central frequency can be tuned thermally from 2 to 40 GHz. The work provides a feasible route to realize a compact, high spectral resolution, and wideband‐tunable MPF on silicon, enabling a range of RF applications from wireless communication to flexible high‐frequency microwave photonic signal processing.

Cascaded traveling wave electrodes designed for group velocity matching in electro-optic modulation

“…High-speed electro-optic (EO) modulator is one of the key elements in various fields, including optical communication 1,2 , microwave photonics 3,4 , and frequency comb generation 5,6 . Traveling wave Mach-Zehnder modulators (TWMZM) have many advantages over microcavity-based EO modulators such as low driving voltage and broadband working wavelength.…”

In situ photoelectric biosensing based on ultranarrowband near-infrared plasmonic hot electron photodetection

“…10 For the latter, the photoelectric responses of most PDs also cover a relatively broad band over 10 nm except the RC PDs, where strong optical resonance via 40 pairs of bottom GaAs/AlAs distributed Bragg reflector (DBR) mirrors and three pairs of top ZnSe∕GaF 2 DBR mirrors contribute to an FWHM of 4 nm. 13 Although microring/microdisk filters with ultrahigh quality (Q) factors can be integrated with waveguide PDs to realize narrowband photodetection, [24][25][26] scaling up the spectral channel meets with significant difficulties due to waveguide coupling and interconnection. In contrast, vertical incidence devices (e.g., focal plane array with millions of pixels) are preferred in high throughput biosensing, spectral imaging, etc.…”

Chip‐Based Microwave Photonic Payload Repeater for High Throughput Satellites

“…[4,5] Compared with microwave IC technology, the PIC can also bring flexibility, scalability, customization, and cost reduction to satellite payloads. [6] So far, on the one hand, PIC work focused on specific RF functionalities such as RF delay lines, [7] optical spectral shaper, [8,9,28] programmable mesh topologies, [10,11,29] and RF photonic integrated filter, [12][13][14][15][16][17][18][19][20][30][31][32][33][34] has been widely reported. Typical photonic integrated filters are based on Mach-Zehnder interferometers (MZI) or ring-assisted MZI (RAMZI) to fulfill diverse functionalities.…”