Generation of a broadband chaotic laser by active optical feedback loop combined with a high nonlinear fiber

Abstract

We propose and demonstrate a method to generate a flat broadband chaotic laser by using an active optical feedback loop combined with a high nonlinear fiber. The feedback strength and nonlinear effect, especially the four-wave mixing effect of high nonlinear fiber, are studied to improve the bandwidth and flatness of chaos. When the feedback strength is 6.6 and injected fiber power is 1.0 W, a chaotic signal with a frequency range over 50 GHz, 80% bandwidth of 38.9 GHz, and flatness of 4.2 dB are experimentally achieved.

Flat broadband chaos generation in a discrete-mode laser subject to optical feedback

“…Optical chaos has many potential applications, such as secure optical communications [1][2][3][4][5][6], time domain reflectometry [7][8], physical random number generation [9][10][11][12][13] and lidar [14], therefore, the generation of optical chaos has attracted significant research interests [15][16][17][18][19][20][21][22][23][24][25][26][27]. Optical chaos generated in semiconductor lasers can be divided into two types [20].…”

“…A flat chaos has been demonstrated in an optical feedback distributed feedback (DFB) laser using a fiber ring resonator which contains an erbium-doped fiber amplifier (EDFA) and a fiber grating [18], and this method has been extended to a VCSEL with a fiber ring resonator, which includes a semiconductor optical amplifier (SOA) and a fiber grating [21]. A very broadband flat chaos was achieved recently using a very strong feedback and long feedback delay time and the use of a highly nonlinear fiber in the feedback loop [27]. The phenomenon of a flat wideband chaos has also been observed in mutually coupled VCSELs by combining two non-uniform chaotic signals [22].…”

Review on the broadband time‐delay‐signature‐suppressed chaotic laser

“…48 Our research group proposed a scheme for the generation of broadband chaotic signal by using a distributed feedback laser diode (DFB-LD) subject to active optical feedback with a HNLF in 2020. 34 The experimental setup is shown in Figure 1 (B1). The output of the DFB-LD is injected into a FC after passing through an OC.…”

“…For example, the active optical feedback with high nonlinear fiber (HNLF) is used to obtain broadband chaos with standard bandwidth of 38.9 GHz. 34 Utilizing random distributed feedback from a fiber random grating, the time-delay signature (TDS) of a chaotic signal is suppressed to 0.0088. 35 Furthermore, a monolithic integrated semiconductor laser has also been designed 36 and produces high-quality chaotic light.…”

Wideband and flat-spectrum chaos generation from a semiconductor laser with strong dispersive light feedback

“…But, from the point view of spectrum flatness, they are not so satisfying because many harmonic peaks appear in the spectrum profile, yielding a flatness significantly higher than 3 dB. Therefore, the methods of delayed self-interference [25], fiber ring resonator [26,27], optical heterodyning [28], optical time lens [29], fiber propagation [30], optical filter [31], self-phase-modulated feedback [32], highly nonlinear fiber [33] are successively proposed to simultaneously widen and flatten the RF spectrum, yielding a spectrum bandwidth approximately at 10 GHz or beyond while maintaining a spectrum flatness around 3 dB. Nevertheless, these methods usually have complex device configurations and require delicate operations because multi parameters should be matched.…”