Experimental and Numerical Study of Locking of Low-Frequency Fluctuations of a Semiconductor Laser with Optical Feedback

Jordi Tiana-Alsina,Cristina Masoller

doi:10.3390/photonics9020103

Jordi Tiana-Alsina, Cristina Masoller

Open Access

https://doi.org/10.3390/photonics9020103

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Abstract

We study the output of a semiconductor laser with optical feedback operated in the low-frequency fluctuations (LFFs) regime and subject to weak sinusoidal current modulation. In the LFF regime, the laser intensity exhibits abrupt drops, after which it recovers gradually. Without modulation, the drops occur at irregular times, while, with weak modulation, they can lock to the external modulation and they can occur, depending on the parameters, every two or every three modulation cycles. Here, we characterize experimentally the locking regions and use the well-known Lang–Kobayashi model to simulate the intensity dynamics. We analyze the effects of several parameters and find that the simulations are in good qualitative agreement with the experimental observations.

Highlights

Locking is a phenomenon that ubiquitously occurs in oscillators that are subject to an external periodic forcing, and refers to the synchronization, or to the adjustment, of the oscillator’s rhythm, to that of the external forcing
The laser intensity shows irregular and abrupt drops, while with current modulation, under appropriate conditions, the spikes lock to the modulation, and they occur with a rhythm that depends on the frequency of the modulation [6,7,8,9,10,11,12,13,14,15,16,17]
We see that for intermediate modulation amplitudes the spikes become periodic and a spike occurs every three modulation cycles

Summary

Introduction

Locking is a phenomenon that ubiquitously occurs in oscillators that are subject to an external periodic forcing, and refers to the synchronization, or to the adjustment, of the oscillator’s rhythm, to that of the external forcing. The laser intensity shows irregular and abrupt drops (that in the following we will refer to as spikes), while with current modulation, under appropriate conditions, the spikes lock to the modulation (see Figure 1), and they occur with a rhythm that depends on the frequency of the modulation [6,7,8,9,10,11,12,13,14,15,16,17]

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