Polarization-independent fiber-chip grating couplers optimized by the adaptive genetic algorithm

Abstract

One-dimensional polarization-independent grating couplers are demonstrated with the aid of the adaptive genetic algorithm optimization. By adjusting the relative weight between the coupling efficiency and the bandwidth of the polarization-dependent loss (PDL), we control the evolution direction and customize the final performance of the device. Two specific designs are generated by giving more weight to the coupling efficiency and the PDL bandwidth, respectively. Coupling efficiencies of the first design are measured to be − 7.6 d B and − 7.9 d B at 1550 nm for TE and TM polarizations, respectively, while its 1.0 dB PDL bandwidth is 25.0 nm. In contrast, the second design presents higher coupling efficiencies of − 7.6 d B and − 7.2 d B at 1550 nm for TE and TM polarizations, respectively. However, its 1.0 dB PDL bandwidth is 22.0 nm.

Silicon and silicon nitride based bilayer polarization-insensitive optical filter

“…An ideal WDM filter requires a flat-passband and broad bandwidth. The Bragg grating filter [6][7][8][9] is a promising candidate due to its unique feature of flat-top response, but it still faces the problem of polarization sensitivity. In the long-range optical fiber transmission system, the polarization of the light signal becomes random.…”

“…On-chip photonic devices are usually designed with only one polarization and use a polarization splitter to separate TE and TM polarizations and handle them separately, but this increases the footprint of the on-chip photonic device. On the other hand, polarization multiplexing has been recognized as a promising approach to extend the data capacity [6]. Therefore, it is urgent to design polarization-insensitive WDM filters with good performance.…”

“…Therefore, it is urgent to design polarization-insensitive WDM filters with good performance. In recent years, many efforts have been made to investigate polarization-insensitive devices [6,[9][10][11][12][13][14][15][16]. However, these methods increase the difficulty of fabrication process and are not CMOS-compatible.…”

A 60 μm-Long Fiber-to-Chip Edge Coupler Assisted by Subwavelength Grating Structure with Ultralow Loss and Large Bandwidth

“…Silicon-on-insulator (SOI), a vital and promising platform for silicon photonics, has attracted tremendous interest to realize compact, high-yield, and energy-efficient photonic integrated circuits (PICs) due to its high refractive-index-contrast and complementary metal-oxide-semiconductor (CMOS) processing [6][7][8][9]. Based on such a material platform, the typical size of a single-mode silicon waveguide is only 220 nm × 450 nm, which poses a huge challenge for efficient light coupling between optical fiber and silicon waveguide since the mode field diameter (MFD) of single-mode fiber (lensed fiber) is about 10 µm (4 µm) [10][11][12]. Therefore, high-performance fiber-to-chip couplers with features of broad bandwidth, low coupling loss, and compact size are our pursuit goals.…”

Manufacture of Three-Dimensional Optofluidic Spot-Size Converters in Fused Silica Using Hybrid Laser Microfabrication

“…In particular, to achieve efficient coupling from optical fibers to on-chip photonic circuits for reducing the mode field mismatching, developing high-performance on-chip waveguide-fiber couplers is of vital importance. Currently, to improve the fiber–chip coupling efficiency, many kinds of on-chip waveguide-fiber couplers, such as grating couplers [ 1 , 2 ], tapered spot-size converters (SSC) [ 3 , 4 , 5 , 6 , 7 ], adiabatically tapered fibers [ 8 , 9 , 10 ], and vertical couplers [ 11 , 12 ], have been developed. Among these optical couplers, SSC structures feature a smooth transition of the mode field and a relatively simple configuration for on-chip photonic integration.…”