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1. A 15-25GHz RF Photonic Front-End with 22nm CMOS Dual-Differential Driver and Silicon Traveling-Wave Mach-Zehnder Modulator

   https://doi.org/10.1364/OFC.2025.Th3J.6  

   Luo, Yu-Lun; Paladugu, Dharma; Madsen, Christi; Entesari, Kamran; Palermo, Samuel (January 2025, Optica Publishing Group)

   A RF photonic front-end using dual-differential driving scheme is reported with a 22nm CMOS FD-SOI driver co-integrated with a silicon traveling-wave Mach-Zehnder modulator. The proposed front-end achieves 15-25GHz bandwidth with 2dBm IIP3 and consumes 448mW. 

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2. A 27.5–46.2-GHz Broadband Low Noise Amplifier With IP3 Enhancement

   https://doi.org/10.1109/LMWT.2023.3283943  

   Hu, Y.; Chi, T. (June 2023, IEEE Microwave and Wireless Technology Letters)

   This letter presents a 27.5–46.2-GHz broadband low-noise amplifier (LNA) featuring IP3 enhancement. The LNA bandwidth (BW) is extended by implementing dual-resonant input matching and a broadband output network. The LNA IP3 is enhanced by incorporating parallel PMOS and NMOS paths in the second stage, with their output currents combined through a three-winding transformer. Implemented using the GlobalFoundries 45-nm CMOS silicon-on insulator (SOI) process, the LNA demonstrates 27.5–46.2 GHz effective BW, 2.1 dB minimum noise figure (NF), and 19.8 dB peak gain. The measured IIP3 is − 3.6 dBm at 34 GHz under 25.5 mW DC power consumption. Compared to recently reported broadband LNAs with a similar frequency range, this design achieves the state-of-the-art NF, IIP3, and figure-of-merit (FoM). 

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3. Modeling and Design of Aperture Coupled Microstrip Patch Antennas with Dual-Offset Feedline

   https://doi.org/10.1109/AP-S/INC-USNC-URSI52054.2024.10685925  

   Claudio, Jan P; Medina, Rafael (July 2024, IEEE)

   This paper describes a methodology for designing feed networks for single-polarized aperture-coupled microstrip patch (ACMP) antennas with dual-offset microstrip feedlines. The method involves characterizing the effective series impedance of the antenna when it is fed in a balanced manner as a function of the distance between the dual feedlines. Fitting equations were generated from the data to relate the effective series impedance to the feed geometry, allowing the design of the matching network for any effective impedance. This work demonstrates that ACMP antennas can be coupled to dual-offset feedlines with λ/4 transformers and T-junctions with infinite combinations of impedance for the λ/4 transformer. A 10 GHz single-polarized ACMP antenna was designed and implemented obtaining satisfactory impedance matching. 

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4. High-Speed CMOS Silicon Photonic PAM4 Transceiver Front-End Circuits

   Palermo, S; Kumar, A; Liu, R; Yuan, Y; Peng, Y; Hong, C; Huang, Z; Kim, I; Fan, Y; Zhu, Y; et al (April 2025, 2025 International VLSI Symposium on Technology, Systems and Applications)

   Growing interconnect bandwidth demand in large datacenters requires energy-efficient optical transceivers that operate with four-level pulse amplitude modulation (PAM4) to enable high per-wavelength data rates. Further increases in bandwidth density is possible by leveraging wavelength-division multiplexing (WDM), which optical link architectures based on silicon photonic microring modulators (MRMs) and drop filters inherently enable. This paper presents high-speed PAM4 transmitter and receiver front-ends implemented in a 28nm CMOS process that are co-designed with these silicon photonic optical devices to enable energy-efficient operation. The transmitter utilizes an optical digital-to-analog converter (DAC) approach with two PAM2 AC-coupled pulsed-cascode high-swing voltage-mode output stages to drive the MRM MSB/LSB segments. A 3.42Vppd output swing is achieved when operating at 80Gb/s PAM4 with an energy efficiency of 3.66pJ/bit. The receiver front-end interfaces with a silicon-germanium avalanche photodiode (APD) and utilizes a low-bandwidth input transimpedance amplifier followed by continuous-time linear equalizer and variable-gain amplifier stages. Biasing the APD to realize a gain of 2 allows for -7dBm optical modulation amplitude (OMA) sensitivity at 56Gb/s PAM4 with a BER=10-4 and an energy efficiency of 1.61pJ/bit. Experimental verification of the full PAM4 transceiver at 50Gb/s operation shows -4.66dBm OMA sensitivity at a BER~4x10-4. 

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5. Nanopatterned parametric oscillators for laser conversion beyond an octave

   https://doi.org/10.1364/OPTICA.545158  

   Brodnik, Grant_M; Liu, Haixin; Carlson, David_R; Black, Jennifer_A; Papp, Scott_B (February 2025, Optica)

   Many uses of lasers place the highest importance on access to specific wavelength bands. For example, mobilizing optical-atomic clocks for a leap in sensing requires compact lasers at frequencies spread across the visible and near-infrared. Integrated photonics enables high-performance, scalable laser platforms. However, customizing laser-gain media to support wholly new bands is challenging and often prohibitively mismatched in scalability to early quantum-based sensing and information systems. Here, we demonstrate a tantalum pentoxide microresonator optical-parametric oscillator (OPO) that converts a pump laser to an output wave within a frequency span exceeding an octave. We control phase matching for oscillation by nanopatterning the microresonator to open a photonic-crystal bandgap on the mode of the pump laser. The photonic crystal splits only the pump mode and preserves the broader mode structure of the resonator, thus affording a single parameter to control output waves across the octave span using a nearly fixed frequency pump laser. We also demonstrate tuning the oscillator in free-spectral-range steps, more finely with temperature, and minimal additive frequency noise of the laser-conversion process. Our work shows that nanophotonic structures offer control of laser conversion in microresonators, bridging phase-matching of nonlinear optics and application requirements for laser designs. 

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