With　the　increasing　capacity　demands　of　data　communications,　mode　division　multiplexing　in　on-chip　optical　interconnect　systems　is　becoming　an　attractive　solution.　Compact,　broadband,　and　fabrication-tolerant　mode-order　converters　unaffected　by　polarizations　are　considered　crucial　for　the　progress　of　on-chip　systems　utilizing　mode　division　multiplexing.　A　proposal　for　a　design　scheme　for　an　on-chip　mode-order　converter　that　is　insensitive　to　polarization　is　presented,　utilizing　a　combination　of　3D　finite-difference　time-domain　(FDTD)　and　particle　swarm　optimization　(PSO).　The　conversion　of　TE0/TM0-to-TE1/TM1　mode　is　achieved　through　phase　matching　between　a　subwavelength　grating　and　an　input–output　tapered　waveguide.　Theoretical　studies　indicate　that　the　TE0-to-TE1　and　TM0-to-TM1　insertion　losses　are　below　0.46　dB　and　0.78　dB　at　a　wavelength　of　1550　nm.　The　TE0-to-TE1　and　TM0-to-TM1　insertion　loss　is　under　1.0　dB,　with　crosstalk　below　−15　dB　within　the　190　nm　(1432∼1622　nm)　and　81　nm　(1515∼1596　nm)　operating　ranges.　Experimental　data　indicates　that　the　device　measuring　7　×　1.58　μm2　can　successfully　convert　mode　orders　regardless　of　polarization　within　an　81　nm　bandwidth　(1515∼1596　nm),　effectively　doubling　the　data　transmission　capacity　of　the　MDM　system.　In　addition,　the　devices　fabricated　by　a　standard　CMOS　process　demonstrate　the　potential　for　mass　production.　©　2024　Elsevier　Ltd