# Synchronized Wavelength-Swept Signal Transmission and its Ability to Evade Optical Reflection Crosstalk

## TL;DR

This paper demonstrates a wavelength-hopping, injection-locked transceiver that significantly reduces reflection crosstalk in optical fiber communication, enhancing robustness against transmission impairments.

## Contribution

It introduces a simple externally modulated laser system with injection-locking that effectively evades optical reflection crosstalk in wavelength-swept signals.

## Key findings

- Reduces reception penalty by over 90% at ~0 dB reflection ratio
- Achieves robust wavelength synchronization with injection-locking
- Mitigates transmission impairments through adaptive sweep parameters

## Abstract

Coherent homodyne detection requires a precise matching of emission wavelengths between transmitter and local oscillator at the receiver. Injection-locking can provide all-optical synchronization of the emission frequencies, even under wavelength-swept emission. By adapting the sweep parameters to the conditions in the optical fiber plant, transmission impairments can be mitigated. In this regard I experimentally demonstrate that a wavelength-hopping yet locked transceiver pair, which builds on conceptually simple externally modulated laser technology, features a much higher robustness to reflection crosstalk. The reception penalty due to distortions arising at a Fresnel reflection in the transmission path can be reduced by >90% at a low optical signal-to-reflection ratio of ~0 dB.

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Source: https://tomesphere.com/paper/1906.02673