We present a systematic scheme to achieve both high birefringence and low confinement loss in index-guiding photonic crystal fibers(PCFs) ,using a structurally-simple PCF with finite number of air holes in the claddin...We present a systematic scheme to achieve both high birefringence and low confinement loss in index-guiding photonic crystal fibers(PCFs) ,using a structurally-simple PCF with finite number of air holes in the cladding region. By increasing the size of the outermost-ring air holes in the cladding region,highly birefringent PCFs with low confinement loss can be successfully achieved. The design strategy is based on the fact that the modal birefringence of PCFs is dominated by the inner-ring air holes in PCF,which is verified by a full-vector finite element method with anisotropic perfectly matched layers. Numerical results show that modal birefringence in the order of 10-3 and confinement loss less than 0.1 dB/km can be easily realized in the proposed PCF with only four rings of air holes in the cladding region. We expect that such fibers will be much easier to be fabvicated than those with more air holes in the cladding region.展开更多
This paper presents a novel self-synchronization scheme utilizing a semiconductor optical amplifier and an optical band-pass filter. Implemented using cross gain modulation and self frequency shift, the proposed schem...This paper presents a novel self-synchronization scheme utilizing a semiconductor optical amplifier and an optical band-pass filter. Implemented using cross gain modulation and self frequency shift, the proposed scheme has a simple structure that does not need any special marker pulses. With proper tuning of semiconductor optical amplifier and optical band-pass filter parameters and delay time of the control pulse, we, through simulation, obtain a synchronization clock with the intensity contrast ratio of more than 20 dB from RZ pseudorandom bit sequence at different operation speeds.展开更多
基金This work hes been is supported in part by National Natural Science Foundation of China (No. 60507007)the Program for New Century Excellent Talents in University (NCET, Min Zhang 2007)
文摘We present a systematic scheme to achieve both high birefringence and low confinement loss in index-guiding photonic crystal fibers(PCFs) ,using a structurally-simple PCF with finite number of air holes in the cladding region. By increasing the size of the outermost-ring air holes in the cladding region,highly birefringent PCFs with low confinement loss can be successfully achieved. The design strategy is based on the fact that the modal birefringence of PCFs is dominated by the inner-ring air holes in PCF,which is verified by a full-vector finite element method with anisotropic perfectly matched layers. Numerical results show that modal birefringence in the order of 10-3 and confinement loss less than 0.1 dB/km can be easily realized in the proposed PCF with only four rings of air holes in the cladding region. We expect that such fibers will be much easier to be fabvicated than those with more air holes in the cladding region.
文摘This paper presents a novel self-synchronization scheme utilizing a semiconductor optical amplifier and an optical band-pass filter. Implemented using cross gain modulation and self frequency shift, the proposed scheme has a simple structure that does not need any special marker pulses. With proper tuning of semiconductor optical amplifier and optical band-pass filter parameters and delay time of the control pulse, we, through simulation, obtain a synchronization clock with the intensity contrast ratio of more than 20 dB from RZ pseudorandom bit sequence at different operation speeds.
