Ultra-high resolution integrated arrayed waveguide spectrometer with reusable delay lines for exoplanet detection

New Integration Photonics, Inc., is proposing to develop an ultra-high resolving power (Rgt;150,000) spectrometer based on arrayed waveguide gratings (AWGs) on a Si3N4/SiO2 photonic integrated chip (PIC). The spectrometer implements a reusable delay line (RDL), replacing the large number of waveguides in the traditional AWG, which significantly reduces the size and increases the stability of the chip. This high-resolution integrated spectrometer can be used in the detection of exoplanets based on the Precision Radial Velocity (PRV) method. The proposed photonic chip has three unique advantages to significantly improve the performance of the traditional spectrometer and increases the feasibility of chip fabrication. 1.By reducing the number of waveguides to just one, and coupling the power from single waveguide to achieve the correct power and phase distributions, the new technique eliminates the need for making large AWGs and the associated step of actively compensating the phase error.nbsp;The footprint of the spectrometer can be potentially reduced by a factor of more than 100. 2. A parabolic taper will be implemented instead of a linear taper before the free propagation region (FPR) to reducing the cross-coupling, and thus the phase distribution error. 3.nbsp;The photonic chip will be directly coupled to a 1-D CCD array in Phase II. To achieve this, a three-stigmatic-points compensation approach is proposed for the RDL-AWG design to realize a flat focal-plane at the output of the free propagating region. It also improves the accuracy and the uniformity of the RDL-AWG and compensates for the aberration.