Observation of binary phase states of time-multiplexed degenerate optical parametric oscillator pulses generated using a nonlinear fiber Sagnac loop

TL;DR

This paper demonstrates the generation and phase bifurcation of over 5,000 time-multiplexed degenerate optical parametric oscillator pulses using a nonlinear fiber Sagnac loop, with potential applications in optical Ising model solving.

Contribution

It introduces a novel fiber Sagnac loop setup for generating large-scale time-multiplexed DOPO pulses with phase bifurcation, enabling scalable optical Ising machines.

Findings

Successfully generated over 5,000 DOPO pulses in a fiber cavity.

Confirmed phase bifurcation to 0 or π, suitable for Ising spin representation.

Verified inherent randomness of DOPO phases with NIST test.

Abstract

We generated time-multiplexed degenerate optical parametric oscillator (DOPO) pulses using a nonlinear fiber Sagnac loop as a phase-sensitive amplifier (PSA) where the pump and amplified light in pump-signal-idler degenerate four-wave mixing can be spatially separated. By placing the PSA in a fiber cavity, we successfully generated more than 5,000 time-multiplexed DOPO pulses. We confirmed the bifurcation of pulse phases to 0 or $\pi$ relative to the pump phase, which makes them useful for representing Ising spins in an Ising model solver based on coherent optical oscillator networks. We also confirmed inherent randomness of the DOPO phases using the NIST random number test.