利用线性IQ调制器抑制谐波串扰的多载波产生方案  

Scheme for Suppressing Harmonic Crosstalk in Multi-Carrier Generation Using Linear IQ Modulator

作　　者：孙璐[1] 林嘉川[1] 李建蕊[1] 唐先锋[1] 席丽霞[1] 张晓光[1] 

机构地区：[1]北京邮电大学信息光子学与光通信国家重点实验室,北京100876

出　　处：《中国激光》2014年第12期107-112,共6页Chinese Journal of Lasers

基　　金：国家自然科学基金(61205065);北京邮电大学信息光子学与光通信国家重点实验室开放课题(IPOC2013B005);北京邮电大学青年科研创新计划(2014RC1201)

摘　　要：为抑制循环频移器(RFS)中IQ调制器的非线性引起的三阶串扰,提高多载波光源输出的平坦度和载噪比,提出了基于线性IQ调制器(LIQM)的循环频移器结构(LIQM-RFS)的多载波产生方案。理论分析得出线性IQ调制器在有效抑制三阶串扰的情况下,对射频信号驱动电压的选择范围是IQ调制器的两倍,特别是能够在一阶信号转换效率较高的范围内实现对三阶串扰的抑制。利用这一特性,基于LIQM-RFS的多载波发生器在保证输出子载波平坦度的同时可以降低所需的掺铒光纤放大器(EDFA)增益,从而降低光纤放大器引起的自发辐射噪声的功率,提高载噪比。仿真结果表明基于LIQM-RFS的多载波发生器输出载波的载噪比较传统RFS提高约9dB,同时可以保证约2.95dB的平坦度。In order to suppress the third-order crosstalk caused by the nonlinearity of the IQ modulator in the recirculating frequency shifter （RFS）, and to improve the flatness of the multi-carriers and carrier to noise ratio （CNR）, a modified RFS scheme based on linear IQ modulator （LIQM-RFS） is presented to generate multi-carriers. According to theoretical analysis, the range of driving voltage of linear IQ modulator （LIQM） radio frequency （RF） source which can be selected is twice of that of IO modulator, with the premise of effective suppression of the third-order crosstalk. In particularly, the third-order crosstalk loss can still be repressed in a range where the first-order harmonic component of LIQM is shifted at a higher efficiency. With this feature, LIQM-RFS-based multi-carrier generator ensures the flatness of subcarriers, meanwhile it requires lower erbium-doped fiber amplifier （EDFA） gain. Therefore, the power of amplified spontaneous emission noise caused by the optical amplifier is lower, by which the CNR is improved. The simulation results show that CNR of multicarrier generated by LIQM-RFS multi-carrier generator increases by about 9 dB compared to traditional RFS, and the subcarrier flatness of about 2.95 dB can be ensured.

关 键 词：光通信 线性IQ调制器 循环频移器 噪声抑制 

分 类 号：TN911.3[电子电信—通信与信息系统]