JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 32, NO. 20, OCTOBER 15, 2014
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Monolithically Integrated Amplified Feedback Lasers for High-Quality Microwave and Broadband Chaos Generation Liqiang Yu, Dan Lu, Biwei Pan, Lingjuan Zhao, Jiagui Wu, Guangqiong Xia, Zhengmao Wu, and Wei Wang
Abstract—The dynamics of monolithically integrated amplified feedback lasers (AFL) is investigated through numerical simulation and experimental verification. The period-doubling route to chaos and high-frequency microwave generation are demonstrated through simulation. Then, we design and fabricate monolithically integrated AFLs. Mappings of dynamic states and oscillation frequency in the parameter space of phase section current IP and amplifier section current IA are depicted. For relative small IA , the period doubling evolution to chaos is presented with the increase of IP . For the relative large IA , a high-frequency mode-beating (M-B) pulsation can be observed under suitable value of IP . The oscillation frequency of period-one is about 10 GHz and the frequency of M-B pulsation is over 40 GHz for the device with a total length of 780 μm. Index Terms—Amplified feedback laser (AFL), chaos, microwave generation.
I. INTRODUCTION ONOLITHICALLY integrated semiconductor lasers (MISL) with optical feedback are of both fundamental and practical importance. Phenomena such as low- and highfrequency oscillation, chaotic behavior, and other dynamics have been theoretically predicted and experimentally measured in MISL. Potential applications include all-optical clock recovery [1], optical microwave generation [2], and chaos generation [3], [4]. The low- and high-frequency oscillations used for clock recovery have been intensively studied in the past ten years [5]–[10]. Recently, the chaotic feature of MISL has attracted significant attention due to their deterministic nature, broadband and noise-like spectral distribution, which are very
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Manuscript received December 2, 2013; revised March 24, 2014; accepted April 22, 2014. Date of publication April 24, 2014; date of current version September 1, 2014. This work was supported in part by the National 973 Program under Grant 2011CB301702, the National 863 Project under Grants 2012AA012203 and 2013AA014202, the National Natural Science Foundation of China under Grants 61201103, 61335009, 61274045, 61205031, 61178011, and 61275116, and the Natural Science Foundation of Chongqing City under Grant 2012jjB40011. L. Yu, D. Lu, B. Pan, L. Zhao, and W. Wang are with the Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Science, Beijing 100083, China (e-mail: yuliqiang10@ semi.ac.cn;
[email protected];
[email protected];
[email protected];
[email protected]). J. Wu, G. Xia, and Z. Wu are with the School of Physics, Southwest University, Chongqing 400715, China (e-mail:
[email protected];
[email protected];
[email protected]). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/JLT.2014.2320371
Fig. 1.
Schematic diagram of the monolithically integrated DFB laser.
attractive in high speed random bit generation [11], [12], chaos synchronization communication [13]–[17], and precision ranging of lidar systems [18]–[20]. Among various MISL, amplified feedback laser (AFL) is a typical and important example, which has been shown to be capable of working in dispersive Q-switching (DQS) pulsation mode, mode-beating (M-B) mode [21] and chaos [22], [23]. A typical AFL consists of a distributed feedback (DFB) laser, a phase section and an active feedback element, as shown in Fig. 1. It is a short photonic circuit that provides several types of dynamics and bifurcations under optical feedback. The dynamics of both DQS and M-B have been reported both theoretically and experimentally [21]. Chaos generators based on MISL (a DFB laser integrated with a passive resonator) were also demonstrated [3], [22], [23]. Due to the long-length resonator design (10650-μm for Ref. [3], [22] and 10700-μm for Ref. [23]), the chaos bandwidth values were limited below 10 GHz. Considering the fact that shortening the external cavity may obtain a higher M-B oscillation frequency [24], [25], we designed a short cavity AFL recently. This type of AFL can be used to generate dual wavelength output with wide frequency separation, as well as a chaos output with broad bandwidth. The short cavity AFL has potential applications in high frequency microwave generation, high speed optical clock recovery and chaos communications. In this letter, we report the simulation, design, and the dynamics of an AFL with short (
