from Rui Cheng, 2019:

I have organized Matlab codes illustrating the design of a 3-channel photonic Hilbert transformer using the Layer Peeling Algorithm (LPA). 

Instructions for the two codes:

Design_3channel_HT.m: 
- Design a 3-channel photonic Hilbert transformer on a 220*500 nm Si waveguide grating [R. Cheng and L. Chrostowski.  Optics Letters 43.5 (2018): 1031-1034]; 
- Using the layer peeling algorithim (LPA) for the grating design synthesis [J. Skaar, et al. IEEE Journal of Quantum Electronics 37.2 (2001): 165-173]

tmmcalc.m: 
- function of the standard coupled mode theory-based transfer matrix method (CMT-TMM) to calculate the grating response