This proposal will design and deliver a novel low-energy switching non-volatile optical memory with > 1 S storage time and ~ 1 PS switching times by coupling improper ferroelectric 2D halide metal…

The Defense Advanced Research Projects Agency awarded a $250,000 Cooperative Agreement to the Trustees of The Colorado School of Mines on September 1, 2026, under the Research and Technology Development program (CFDA 12.910) to design and deliver a novel low-energy switching non-volatile optical memory with storage times exceeding one second and switching times of approximately one picosecond by coupling improper ferroelectric two-dimensional halide metal halide perovskite materials with silicon nitride waveguides.

The recipient will fabricate photonic integrated circuit devices via low-temperature thermal evaporation to deposit high optical quality thin films compatible with existing back-end-of-line foundry processes. Preliminary results demonstrate switching at 0.01 joules per cubic centimeter, compared to state-of-the-art phase-change and magneto-optic optical memories operating at one to one hundred joules per cubic centimeter. The approach leverages aligned refractive indices between the perovskite material and silicon nitride waveguides to achieve optical storage and retrieval efficiencies exceeding ninety percent. The core challenge addresses identifying materials with memory states that can be optically written within picoseconds and read over millisecond timescales with cycling endurance exceeding one trillion cycles. Chiral two-dimensional halide metal halide perovskite materials exhibit tunable multiferroic properties coupling optical, ferroelectric, and magnetic characteristics, providing multiple approaches to write and read optical memories. Prior thermal vapor deposition innovations enable non-volatile all-optical writing and readout via efficient ferroelectric domain switching by photogenerated spins.

Work is performed in Golden, Colorado. The award runs through August 31, 2028.

This proposal will design and deliver a novel low-energy switching non-volatile optical memory with > 1 S storage time and ~ 1 PS switching times by coupling improper ferroelectric 2D halide metal halide perovskite (MHP) materials with SIN waveguides. We will create photonic integrated circuit (PIC) devices via low-temperature thermal evaporation, which we have demonstrated deposits high optical quality thin films on SIN and which is compatible with existing back-end-of-line (BEOL) foundry processes. Compared to state-of-the-art phase-change material and magneto-optic optical memories (~ 1-100 J/CM3), our unoptimized preliminary results achieve switching at 0.01 J/CM3 (60 FJ). Strong oscillator strengths and aligned refractive index (N_SIN = 2.00 VS. N_MHP = 1.98) maximize the interaction of waveguide modes with the MHP material to enable optical storage and retrieval efficiencies of >90%. The core challenge for optical memories is identifying a material with memory states that can be optically written within ~ PS and read over > MS times with cycling endurance > 1012. State-of-the-art approaches lack these traits due to material limitations: phase change materials have insufficient switching speed and endurance; photonic memristors lack endurance; and magneto-optic materials are incompatible with foundry processes. Chiral 2D MHP materials exhibit unique tunable multiferroic properties, which couple their optical, ferroelectric, and magnetic properties, as well as phase transitions, providing multiple approaches to write and read optical memories. Despite their promise, mhps have not been explored for pics because they are primarily made with solution processing and lack sufficient optical quality. We have recently demonstrated two key innovations that enable MHP optical memories for the first time: non-volatile all-optical writing and readout via efficient switching of ferroelectric domains by photogenerated spins; and vapor deposition of mhps with sufficient optical quality for pics. This unique switching mechanism is enabled by the tunable ferroelectric properties and soft lattice of mhps. Rather than creating highly stable ferroelectric domains with significant barriers for switching, we instead target a goldilocks regime with low coercive fields and barriers for switching, where spin and photostriction destabilization are sufficient to drive switching due to coupled properties. While we target writable storage times ~ 1 S for network buffering and dram, this platform is highly flexible, enabling tunable storage times from ~ FS to > 1000 S. Achieving this vision requires demonstrating BEOL deposition with minimum roughness and accessing appropriate coercive fields (E_C). These two aims form the basis of this proposal. This YFA proposal is built on an aggressive experimental plan to demonstrate a PIC optical memory compatible with foundry processes and with 50°C. Improving thermal evaporation and post-processing to achieve < 4 NM RMS of MHP thin films and control of orientation (enabling losses < 1 DB/CM and ~ 20 FJ/switch). As an option target, we will expand these designs to spin-based memories that utilize the exceptional magneto-optical properties of mhps to induce strong FS ¿ 10 NS volatile memory states necessary for optical network protocol buffering. This proposal initializes a new material class for rapid adoption in PIC designs with unprecedented control over storage time, switching mechanism, and optical properties tunable from UV to MIR. Low deposition costs ~ $1/M2 are feasible.