Phase II Active Low-Voltage Thin-Film Lithium Niobate Electro-Optic Modulator

Microwave photonics (MWP) offers many advantages for analog signal processing: operation across large frequency ranges with wide bandwidths, low-loss signal transport via optical fiber with excellent immunity to electromagnetic interference, low return loss and high isolation with switches and circulators, among many others. But the conversion of an electrical signal to an optical signal has historically been so poor, it has kept MWP from being implemented. An electro-optic modulator must have strong conversion efficiency, low insertion loss, a flat frequency response, and a high optical power threshold to enable the many possible applications of MWP systems.In response to this need, Critical Frequency Design (CFD) proposes the development of an electro-optic modulator with low half-wave voltage (Vpi) using thin-film lithium niobate (TFLN), coupled with a high-power optical amplifier integrated in a small, durable package. By leveraging the latest breakthroughs in chip-scale optical amplifiers and TFLN processing, combined with innovative packaging methods, CFD will produce an active modulator with sufficiently high performance to enable a balanced intensity modulation direct detection (IMDD) link with 3 dB noise figure (NF) and 116 dB*Hz2/3 spur-free dynamic range (SFDR).Two main parameters contribute significantly to the RF performance of an IMDD link: modulator half-wave voltage (Vpi) and optical power into the modulator. NF improves with lower Vpi and higher optical power, while SFDR depends more strongly on optical power but can be reduced when Vpi is low enough that the overall link gain is large and input thermal noise becomes the dominant noise term. To achieve the desired RF metrics of 3 dB NF and 116 dB*Hz2/3 SFDR, a modulator with 0.5 V Vpi and 30 dBm optical input power is needed. This project will produce a small form factor active modulator capable of maintaining such high performance in harsh environments, which will in turn enable a wide range of applications for RF and microwave systems.