Citation: 
Yunshan Zhang, Yifan Xu, Shijian Guan, Jilin Zheng, Hongming Gu, Lianyan Li, Rulei Xiao, Tao Fang, Hui Zou, Xiangfei Chen. Modulation bandwidth enhancement in monolithic integrated twosection DFB lasers based on the detuned loading effect[J]. Journal of Semiconductors, 2023, 44(11): 112301. doi: 10.1088/16744926/44/11/112301
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Yunshan Zhang, Yifan Xu, Shijian Guan, Jilin Zheng, Hongming Gu, Lianyan Li, Rulei Xiao, Tao Fang, Hui Zou, Xiangfei Chen. 2023: Modulation bandwidth enhancement in monolithic integrated twosection DFB lasers based on the detuned loading effect. Journal of Semiconductors, 44(11): 112301. doi: 10.1088/16744926/44/11/112301

Modulation bandwidth enhancement in monolithic integrated twosection DFB lasers based on the detuned loading effect
DOI: 10.1088/16744926/44/11/112301
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Abstract
Modulation bandwidth enhancement in a directly modulated twosection distributed feedback (TSDFB) laser based on a detuned loading effect is investigated and experimentally demonstrated. The results show that the 3dB bandwidth of the TSDFB laser is increased to 17.6 GHz and that chirp parameter can be reduced to 2.24. Compared to the absence of a detuned loading effect, there is a 4.6 GHz increase and a 2.45 reduction, respectively. After transmitting a 10 Gb/s nonreturntozero (NRZ) signal through a 5km fiber, the modulation eye diagram still achieves a large opening. Eightchannel laser arrays with precise wavelength spacing are fabricated. Each TSDFB laser in the array has side mode suppression ratios (SMSR) > 49.093 dB and the maximum wavelength residual < 0.316 nm. 
References
[1] Ishikawa T, Higashi T, Uchida T, et al. Evaluation of differential gain of 1.3/spl mu/m AlGaInAs/InP strained MQW lasers. Conference Proceedings. 1998 International Conference on Indium Phosphide and Related Materials (Cat. No. 98CH36129), 2002, 729 doi: 10.1109/ICIPRM.1998.712746[2] Morthier G. Design and optimization of strainedlayermultiquantumwell lasers for highspeed analog communications. IEEE J Quantum Electron, 1994, 30, 1520 doi: 10.1109/3.299483[3] Otsubo K, Matsuda M, Takada K, et al. 1.3μm AlGaInAs multiplequantumwell semiinsulating buriedheterostructure distributedfeedback lasers for highspeed direct modulation. IEEE J Sel Top Quantum Electron, 2009, 15, 687 doi: 10.1109/JSTQE.2009.2015194[4] Nakahara K, Wakayama Y, Kitatani T, et al. Direct modulation at 56 and 50 Gb/s of 1.3μm InGaAlAs ridgeshapedBH DFB lasers. IEEE Photonics Technol Lett, 2015, 27, 534 doi: 10.1109/LPT.2014.2384520[5] Kobayashi W, Tadokoro T, Ito T, et al. Highspeed operation at 50 Gb/s and 60km SMF transmission with 1.3μm InGaAlAsbased DML. ISLC 2012 International Semiconductor Laser Conference, 2012, 50 doi: 10.1109/ISLC.2012.6348329[6] Sakaino G, Takiguchi T, Sakuma H, et al. 25.8Gbps direct modulation of BH AlGaInAs DFB lasers with pInP substrate for low driving current. 22nd IEEE International Semiconductor Laser Conference, 2010, 197 doi: 10.1109/ISLC.2010.5642644[7] Tadokoro T, Kobayashi W, Fujisawa T, et al. 43 Gb/s 1.3 μm DFB laser for 40 km transmission. J Light Technol, 2012, 30, 2520 doi: 10.1109/JLT.2012.2203095[8] Uetake A, Otsubo K, Matsuda M, et al. 40Gbps direct modulation of 1.55µm AlGaInAs semiinsulating buriedheterostructure distributed reflector lasers up to 85°C. 2009 IEEE LEOS Annual Meeting Conference Proceedings, 2009, 839 doi: 10.1109/LEOS.2009.5343421[9] Henry C. Performance of distributed feedback lasers designed to favor the energy gap mode. IEEE J Quantum Electron, 1985, 21, 1913 doi: 10.1109/JQE.1985.1072611[10] Matsui Y, Schatz R, Che D. Isolatorfree > 67GHz bandwidth DFB+R laser with suppressed chirp. 2020 Optical Fiber Communications Conference and Exhibition, 2020, 1 doi: 10.1364/OFC.2020.Th4A.1[11] Che D, Matsui Y, Schatz R, et al. Direct modulation of a 54GHz distributed Bragg reflector laser with 100GBaud PAM4 and 80GBaud PAM8. 2020 Optical Fiber Communications Conference and Exhibition (OFC), 2020, 1 doi: 10.1364/OFC.2020.Th3C.1[12] Guan S J, Zhang Y S, Zheng J L, et al. Modulation bandwidth enhancement and frequency chirp suppression in twosection DFB laser. J Light Technol, 2022, 40, 7383 doi: 10.1109/JLT.2022.3203723[13] Zhao W, Mao Y F, Lu D, et al. Modulation bandwidth enhancement of monolithically integrated mutually coupled distributed feedback laser. Appl Sci, 2020, 10, 4375 doi: 10.3390/app10124375[14] Yamaoka S, Diamantopoulos N P, Nishi H, et al. Directly modulated membrane lasers with 108 GHz bandwidth on a highthermalconductivity silicon carbide substrate. Nat Photonics, 2021, 15, 28 doi: 10.1038/s4156602000700y[15] Matsui Y, Schatz R, Che D, et al. Lowchirp isolatorfree 65GHzbandwidth directly modulated lasers. Nat Photonics, 2021, 15, 59 doi: 10.1038/s41566020007422[16] Yuan B C, Shi J Q, Qi W X, et al. A monolithic integrated dualwavelength DFB laser with equivalent inverseGaussian apodized grating. IEEE Photonics J, 2020, 12, 1 doi: 10.1109/JPHOT.2020.3030669[17] Guan S J, Zhang Y S, Yuan B C, et al. Research on the asymmetric corrugationpitchmodulated HRAR DFB lasers with sampled gratings. J Light Technol, 2021, 39, 4725 doi: 10.1109/JLT.2021.3075484[18] Zhang Y S, Yuan B C, Shi J Q, et al. A stable dualwavelength DFB semiconductor laser with equivalent chirped sampled grating. IEEE J Quantum Electron, 2022, 58, 1 doi: 10.1109/JQE.2022.3223172[19] Vieu C, Carcenac F, Pépin A, et al. Electron beam lithography: Resolution limits and applications. Appl Surf Sci, 2000, 164, 111 doi: 10.1016/S01694332(00)003524[20] Dai Y T, Chen X F, Xia L, et al. Sampled Bragg grating with desired response in one channel by use of a reconstruction algorithm and equivalent chirp. Opt Lett, 2004, 29, 1333 doi: 10.1364/OL.29.001333[21] Sun Z X, Xiao R L, Zhao Y, et al. Design of fourchannel wavelengthselectable Inseries DFB laser array with 100GHz spacing. J Light Technol, 2020, 38, 2299 doi: 10.1109/JLT.2020.2970788[22] Bandelow U, Schatz R, Wunsche H J. A correct singlemode photon rate equation for multisection lasers. IEEE Photonics Technol Lett, 1996, 8, 614 doi: 10.1109/68.491556[23] Chaciński M, Schatz R. Impact of losses in the Bragg section on the dynamics of detuned loaded DBR lasers. IEEE J Quantum Electron, 2010, 46, 1360 doi: 10.1109/JQE.2010.2048013[24] Devaux F, Sorel Y, Kerdiles J F. Simple measurement of fiber dispersion and of chirp parameter of intensity modulated light emitter. J Light Technol, 1993, 11, 1937 doi: 10.1109/50.257953 
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