Dispersive optical phased arrays(DOPAs)offer a method for fast 2D beam scanning for solid-state LiDAR with a pure passive operation,and therefore low control complexity and low power consumption.However,in terms of sc...Dispersive optical phased arrays(DOPAs)offer a method for fast 2D beam scanning for solid-state LiDAR with a pure passive operation,and therefore low control complexity and low power consumption.However,in terms of scalability,state-of-the-art DOPAs do not easily achieve a balanced performance over the specifications of longrange LiDAR,including the number of pixels(resolvable points)and beam quality.Here,we experimentally demonstrate the pixelated DOPA concept,which overcomes the scaling challenges of classical(continuous)DOPAs by introducing a new design degree of freedom:the discretization of the optical delay lines distribution network into blocks.We also present the first demonstration of the unbalanced splitter tree architecture for the DOPA distribution network,incorporated in both the continuous DOPA and the pixelated DOPA variations.The small-scale demonstration circuits can scan over a field of view of 15°×7.2°,where the continuous DOPA provides 16×25 pixels,while the pixelated DOPA provides 4×25 pixels,for a 1500 to 1600 nm wavelength sweep.The pixelated DOPA exhibits a side lobe suppression ratio with a median of 7.6 dB,which is higher than that of the continuous version,with a median of 3.6 dB.In addition,the ratio of the main beam to the background radiation pattern is 11 dB(median value)for the pixelated DOPA,while for the continuous DOPA,it is 9.5 dB.This is an indication of a higher beam quality and lower phase errors in the pixelated DOPA.The degree of discretization,combined with other design parameters,will potentially enable better control over the beam quality,while setting practical values for the number of pixels for large-scale DOPAs.展开更多
Leveraging its superior waveguide properties,silicon-nitride(Si_(3)N_(4))photonics is emerging to expand the applications of photonic integrated circuits to optical systems where bulk optics and fibers today still dom...Leveraging its superior waveguide properties,silicon-nitride(Si_(3)N_(4))photonics is emerging to expand the applications of photonic integrated circuits to optical systems where bulk optics and fibers today still dominate.In order to fully leverage its advantages,heterogeneous integration ofⅢ-Ⅴgain elements on Si_(3)N_(4)is one of the most critical steps.In this paper,we demonstrate aⅢ-Ⅴ-on-Si_(3)N_(4)widely tunable narrow-linewidth laser based on micro-transfer printing.Detailed design considerations of the tolerantⅢ-Ⅴ-to-Si_(3)N_(4)vertical coupler,Si_(3)N_(4)-based micro-ring resonators(MRRs),and micro-heaters are discussed.By introducing the dispersion of Si_(3)N_(4)waveguide in the design,the proposed Vernier MRRs enable an extended tuning range over multiple Vernier periods.The laser shows a wavelength tuning range of 54 nm in C and L bands with intrinsic linewidth less than 25 kHz.Within the tuning range,the side mode suppression ratio is larger than 40 dB and the output power in the Si_(3)N_(4)waveguide reaches 6.3 mW.The integration process allows for the fabrication and quality control of both the Si_(3)N_(4)circuits andⅢ-Ⅴdevices in its own foundry,which greatly enhances the integration yield and paves the way for large-scale integration.展开更多
文摘Dispersive optical phased arrays(DOPAs)offer a method for fast 2D beam scanning for solid-state LiDAR with a pure passive operation,and therefore low control complexity and low power consumption.However,in terms of scalability,state-of-the-art DOPAs do not easily achieve a balanced performance over the specifications of longrange LiDAR,including the number of pixels(resolvable points)and beam quality.Here,we experimentally demonstrate the pixelated DOPA concept,which overcomes the scaling challenges of classical(continuous)DOPAs by introducing a new design degree of freedom:the discretization of the optical delay lines distribution network into blocks.We also present the first demonstration of the unbalanced splitter tree architecture for the DOPA distribution network,incorporated in both the continuous DOPA and the pixelated DOPA variations.The small-scale demonstration circuits can scan over a field of view of 15°×7.2°,where the continuous DOPA provides 16×25 pixels,while the pixelated DOPA provides 4×25 pixels,for a 1500 to 1600 nm wavelength sweep.The pixelated DOPA exhibits a side lobe suppression ratio with a median of 7.6 dB,which is higher than that of the continuous version,with a median of 3.6 dB.In addition,the ratio of the main beam to the background radiation pattern is 11 dB(median value)for the pixelated DOPA,while for the continuous DOPA,it is 9.5 dB.This is an indication of a higher beam quality and lower phase errors in the pixelated DOPA.The degree of discretization,combined with other design parameters,will potentially enable better control over the beam quality,while setting practical values for the number of pixels for large-scale DOPAs.
文摘Leveraging its superior waveguide properties,silicon-nitride(Si_(3)N_(4))photonics is emerging to expand the applications of photonic integrated circuits to optical systems where bulk optics and fibers today still dominate.In order to fully leverage its advantages,heterogeneous integration ofⅢ-Ⅴgain elements on Si_(3)N_(4)is one of the most critical steps.In this paper,we demonstrate aⅢ-Ⅴ-on-Si_(3)N_(4)widely tunable narrow-linewidth laser based on micro-transfer printing.Detailed design considerations of the tolerantⅢ-Ⅴ-to-Si_(3)N_(4)vertical coupler,Si_(3)N_(4)-based micro-ring resonators(MRRs),and micro-heaters are discussed.By introducing the dispersion of Si_(3)N_(4)waveguide in the design,the proposed Vernier MRRs enable an extended tuning range over multiple Vernier periods.The laser shows a wavelength tuning range of 54 nm in C and L bands with intrinsic linewidth less than 25 kHz.Within the tuning range,the side mode suppression ratio is larger than 40 dB and the output power in the Si_(3)N_(4)waveguide reaches 6.3 mW.The integration process allows for the fabrication and quality control of both the Si_(3)N_(4)circuits andⅢ-Ⅴdevices in its own foundry,which greatly enhances the integration yield and paves the way for large-scale integration.
