Phase calibration for optical phased arrays(OPAs) is a key process to compensate for the phase deviation and retrieve the initial working state. Conventional calibration approaches based on iterative optimization algo...Phase calibration for optical phased arrays(OPAs) is a key process to compensate for the phase deviation and retrieve the initial working state. Conventional calibration approaches based on iterative optimization algorithms are tedious and time-consuming. The essential difficulty of such a problem is to inversely solve for the phase error distribution among OPA elements from the far-field pattern of an OPA. Deep-learning-based technology might offer an alternative approach without explicitly knowing the inverse solution. However, we find that the phase ambiguities, including conjugate ambiguity and periodic ambiguity, severely deter the accuracy and efficacy of deep-learning-based calibration. Device-physics-based analysis reveals the causes of the phase ambiguities, which can be resolved by creating a tailored artificial neural network with phase-masked far-field patterns in a conjugate pair and constructing a periodic continuity-preserving loss function. Through the ambiguity-resolved neural network, we can extract phase error distribution in an OPA and calibrate the device in a rapid, noniterative manner from the measured far-field patterns. The proposed approach is experimentally verified. Pure main-beam profiles with >12 dB sidelobe suppression ratios are observed. This approach can help overcome a crucial bottleneck for the further advance of OPAs in a variety of applications such as lidar.展开更多
A simple method for improving grating couplers' coupling efficiency without any extra microfabrication processes is proposed. This method can improve the coupling efficiency with 1.69 dB by utilizing the combined ...A simple method for improving grating couplers' coupling efficiency without any extra microfabrication processes is proposed. This method can improve the coupling efficiency with 1.69 dB by utilizing the combined interference in the cladding layer and air gap between the cladding surface and the paralleled angle polished fiber facet. The proposed method can be applied to various kinds of on-chip grating couplers. Back reflection,1 dB bandwidth, and fiber alignment tolerance have also been improved at the same time.展开更多
基金National Natural Science Foundation of China(62175103, 61775094)Jiangsu Innovation TeamsNational Key Research and Development Program of China(2017YFA0303700)。
文摘Phase calibration for optical phased arrays(OPAs) is a key process to compensate for the phase deviation and retrieve the initial working state. Conventional calibration approaches based on iterative optimization algorithms are tedious and time-consuming. The essential difficulty of such a problem is to inversely solve for the phase error distribution among OPA elements from the far-field pattern of an OPA. Deep-learning-based technology might offer an alternative approach without explicitly knowing the inverse solution. However, we find that the phase ambiguities, including conjugate ambiguity and periodic ambiguity, severely deter the accuracy and efficacy of deep-learning-based calibration. Device-physics-based analysis reveals the causes of the phase ambiguities, which can be resolved by creating a tailored artificial neural network with phase-masked far-field patterns in a conjugate pair and constructing a periodic continuity-preserving loss function. Through the ambiguity-resolved neural network, we can extract phase error distribution in an OPA and calibrate the device in a rapid, noniterative manner from the measured far-field patterns. The proposed approach is experimentally verified. Pure main-beam profiles with >12 dB sidelobe suppression ratios are observed. This approach can help overcome a crucial bottleneck for the further advance of OPAs in a variety of applications such as lidar.
基金supported by the National Key R&D Program of China (Nos. 2017YFA0303700 and 2017YFA0303704)the National Natural Science Foundation of China (Nos. 61775094 and 41427801)+1 种基金the Fundamental Research Funds for the Central Universities (No. 021314380072), the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘A simple method for improving grating couplers' coupling efficiency without any extra microfabrication processes is proposed. This method can improve the coupling efficiency with 1.69 dB by utilizing the combined interference in the cladding layer and air gap between the cladding surface and the paralleled angle polished fiber facet. The proposed method can be applied to various kinds of on-chip grating couplers. Back reflection,1 dB bandwidth, and fiber alignment tolerance have also been improved at the same time.
