Broadband Enhancement of Optical Frequency Comb Using Cascaded Four-Wave Mixing in Photonic Crystal Fiber

Tawfig Eltaif

doi:10.1155/2017/1365072

Abstract

A cascaded intensity modulator (IM) and phase modulator (PM) are used to modulate a continuous-wave (CW) laser and generate an optical frequency comb (OFC). Thus, the generated comb is utilized as an initial seed and combined with another CW-laser to generate four-wave mixing (FWM) in photonic crystal fiber (PCF). Results show that an initial flat 30 GHz OFC of 29, 55 lines within power fluctuation of 0.8 dB and 2 dB, respectively, can be achieved by setting the ratio of the DC bias to amplitude of sinusoidal signal at 0.1 and setting the modulation indices of both IM and PM at 10. Moreover, the 1st order of FWM created through 14 m of PCF has over 68 and 94 lines with fluctuation of 0.8 dB and 2 dB, respectively. Hence, the generated wavelengths of 1st left and right order of FWM can be tuned in a range from ~1500 nm to ~1525 nm and ~1590 nm to ~1604 nm, respectively.

Highlights

The generated wavelengths of 1st left and right order of four-wave mixing (FWM) can be tuned in a range from ∼1500 nm to ∼1525 nm and ∼1590 nm to ∼1604 nm, respectively
Generation of four-wave mixing (FWM) in highly nonlinear low-dispersion fibers was intensively studied, so it can be utilized as an optical source for wavelength-division multiplexing (WDM) system [1,2,3,4]
As the new lines propagate along the fiber, interaction of the lines with each other occurred, and cascaded FWM

Summary

Introduction

Generation of four-wave mixing (FWM) in highly nonlinear low-dispersion fibers was intensively studied, so it can be utilized as an optical source for wavelength-division multiplexing (WDM) system [1,2,3,4]. Optical frequency comb is very useful for high-repetition-rate pulse train generation [14] and for injection locking of widely separated lasers [15]. Such OFC can reduce the cost of WDM system, where many wavelengths can be generated and each can be used to carry single user’s data [16]. In this paper, with advantages of nonlinear optics effect of intensity modulator (IM) followed by phase modulator (PM) and FWM caused by two laser sources over m of photonic crystal fiber cascaded four-wave mixing was achieved.

System Setup

Findings

System Evaluation