PROGRAM | Electrical & Computer Engineering

By: Md Jubayer Shawon Chair: Vishal Saxena

ABSTRACT

Traditional RF photonic systems have relied on discrete photonic components which are costly, inefficient, and power-hungry. In contrast, silicon-based RF photonics leverages the mature CMOS processes developed in the semiconductor industry, enabling the integration of electronics with Photonic Integrated Circuits (PICs) on a large scale. Therefore, this work aims to address several challenges of Silicon Photonics based PICs for RF photonics and optical signal processing applications.

1. Photonic Integrated Circuit Simulation Using Verilog-A Compact Models:

Achieving successful integration of Silicon Photonic Integrated Circuits (PIC) with RF electronics necessitates a common design and verification platform capable of co-simulating both photonic and electronic circuits. The design tools for photonic integrated circuits (PICs) have evolved independently from electronic circuit simulation tools, resulting in a disconnection between these two domains. Bridging this gap is essential to enable efficient co-simulation of photonic circuits with interfacing electronic circuits. To address this, the current work introduces a complex frequency chirp-based method in Verilog-A for rapid frequency-domain simulation of PICs in Cadence platform. The presented method can result in over 1000x improvement in the simulation time of frequency sweeps of higher-order optical resonant circuits.

2. Linearized Ring Assisted Mach Zehnder Modulator:

In a high-performance RF photonic system, Electro-Optic (EO) modulators play a crucial role as a key component, requiring high linearity. While traditional lithium niobate Mach-Zehnder Modulators have been widely used due to their superior linearity, silicon-based EO modulators have not achieved the same level of performance. To address this, the present work focuses on the experimental demonstration of a Ring Assisted Mach Zehnder Modulator (RAMZM). This modulator allows for linearization in the optical domain, and can be reconfigured to linearize around a user-specified center frequency and bias conditions. The modulator achieves a spurious-free dynamic range (SFDR) exceeding 113 dB.Hz^2/3.

3. Reconfigurable Silicon Photonic Optical Filters:

In flexible RF photonic systems, it is crucial for optical filters to have tunability across a broad range of center frequencies. Additionally, these filters are expected to be frequency agile, meaning that their tunability and reconfigurability should be rapid and automatic. Therefore, this work demonstrates a software-configurable integrated optical filter capable of on-the-fly reconfiguration based on user specifications (filter topology, center frequency, bandwidth, and rejection). A second-order filter with 3dB bandwidth of 3 GHz, 2.2 dB insertion loss and >30 dB out-of-band rejection using only two reference laser wavelength settings has been presented.

4. Silicon Photonic Reconfigurable Optical Analog Processor:

Designing application-specific photonic integrated circuits (PICs) involves complex and time-consuming design cycles such as simulation, layout, fabrication, packaging, and testing, which require significant engineering effort and incur high costs. To address this challenge, the introduction of a general-purpose reconfigurable PIC holds the potential to revolutionize the field of integrated photonics, similar to the impact of electronic field-programmable gate arrays (FPGAs) in the electronics industry. Such a reconfigurable PIC would enable rapid design exploration and could cut the design cycle time from months to just a few hours. Therefore, in this work, general-purpose silicon photonics-enabled optical mesh structures have been explored. These structures are fabricated using a CMOS-compatible SiP foundry process and interfaced with electronic hardware backend. A wide range of optical circuits can be synthesized within these meshes.

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