Fig. 1. Schematic of operating principle of CPA

Fig. 2. Schematic of MMDG structure

Fig. 3. Experimentally measured spectra of -1^st order diffraction efficiency and 0^th order reflection efficiency of TE polarization with 50° incident angle^[23]

Fig. 4. Reflectivity of MLD and MMLD measured for TE polarization with 70.6° incident angle ^[21]

Fig. 5. Broadband diffraction efficiency spectrum of MMDG^[27]

Fig. 6. Broadband diffraction efficiency of MMDG^[28]

Fig. 7. Ultrabroad diffraction efficiency of MMDG. MMDG parameters are 315 nm, 173 nm,140 nm, and 0.25^[35]

Fig. 8. Diffraction efficiencies of the -1^st order for both TE and TM polarizations^[36]

Fig. 9. Relationship between bandwidth and maximum electric field in Ag layer^[37]

Fig. 10. Structure of MMDG proposed in Ref. [38]