Research On High-contrast Sub-wavelength Grating In Optoelectronic Integrated Devices

Because of its simple structure and flexible design,diffraction grating has become a common optical instrument and occupies an important position in optics.With the continuous progress of the research,the development of the grating is changing with each passing day.Under such background,high contrast sub-wavelength grating with its unique advantages has been wildly used for the optoelectronic devices such as filters,lasers and detectors.Through the reasonable design of grating structure parameters,we can not only get the required reflectivity and bandwidth,but also achieve the control of beam propagation direction,so as to achieve different functions.Based on phase regulation,we carried out the research on high contrast sub-wavelength grating,and considered optimization throughout the process.The main content and innovations of this paper are as follows:1.Based on light field control mechanism of the high contrast sub-wavelength grating,non-periodic strip high contrast sub-wavelength grating and polarization-insensitive two-dimensional high contrast sub-wavelength grating with focusing function have been designed.And the optimal design schemes of two-dimensional high contrast sub-wavelength grating are also put forward.2.The subwavelength grating size effect that the focal length change with the size of the design grating was discovered and studied.The simulation results show that because of the influence of diffraction,a larger grating reflector size,with a phase difference of at least 3?between center and edge of grating,will have a stable focal length which is close to the design.This research has considerable guiding significance for the precise design of the subsequent converging grating in optoelectronic integrated devices.3.The polarization-independent focusing reflector using two-dimensional subwavelength grating has been both numerically and experimentally demonstrated.The focusing reflector with a focal length of 6 ?m and a grating area of 10.5 ?m × 10.5 ?m was investigated.Setting up test system,the results exhibited the focusing ability without polarization sensitivity under normal incident light at wavelength 1.55?m.The numerical aperture is 0.66 and the convergence efficiency is over 82%.In the reflection focal plane,the full-width-half-maximum of the electric field intensity is 1.338 ?m.