Abstract

This paper proposes a novel on-chip optical pulse train generator (OPTG) based on optomechanical oscillation (OMO). The OPTG consists of an optical cavity and mechanical resonator, in which OMO periodically modulates the optical cavity field and consequently generates optical pulse trains. The dimensionless method are introduced to simulate the OMO-based OPTG with reduced analysis complexity. We investigate the optomechanical coupling and the dynamic back-action processes, by which we found a dead zone that forbids the OMO, and derived the optimal laser detuning and the minimum threshold power. We analysed the OMO-based OPTG in terms of the pulse shape distortion, extinction ratio (ER) and duty-cycle (DC). Increasing input power, mechanical and optical Q-factors will increase ER, reduce DC and produce sharper and shorter optical pulses. We also discuss the design guidance of OMO-based OPTG and explore its application in distributed fibre optical sensor (DFOS).

Highlights

  • Optical pulse train generators (OPTG) are essential for many applications, such as optical communication [1], microwave photonics [2] and sensing system [3]

  • This paper investigates the novel approach of realising on-chip optical pulse train generator (OPTG) with optomechanical oscillation (OMO) and is organised as follow: Section 2 introduces the theoretical model based on four independent dimensionless parameters to analytically and numerically investigate the OMO process

  • The OMO-based OPTG is formed by suspending part of a racetrack-shape microresonator, where the suspended beam serves as the mechanical resonator and coupled to the optical cavity

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Summary

Introduction

Optical pulse train generators (OPTG) are essential for many applications, such as optical communication [1], microwave photonics [2] and sensing system [3]. Integrated optical pulse generation is achieved by a few approaches, including mode-locked semiconductor lasers [5, 6], microresonator-based Kerr soliton frequency comb [7, 8] and on-chip optical modulator [9, 10]. The approach of microresonator-based Kerr soliton frequency comb inputs a narrow-band laser source into an optical microresonator with high quality factor, and uses the cascaded four-wave-mixing process to generate optical pulses. [11] proposed to use optomechanical systems to generate optical frequency sidebands. This method involves a parametric process and potentially can be utilised to generate time-domain pulse trains based on Fourier transformation.

Theoretical model based on dimensionless parameters
Dynamic back-action and OMO threshold
Frequency sideband formation and optical pulse generation
Optical pulse characteristics and parameter analysis
Optomechanical system design
Pulse generation for DFOS
Rectangular
Discussion and conclusion
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