It　is　hard　to　design　a　traditional　edge-lit　light　guide　plate　(LGP)　as　an　ultrathin　structure,　because　the　LGP　thickness　will　be　limited　by　the　luminescence　regional　width　of　the　LED　source.　In　this　paper,　a　tilted　light　coupling　structure　(TLCS)　for　a　liquid　crystal　display　(LCD)　backlight　is　proposed　that　allows　an　inclined　layout　of　an　edge　LED　array　to　significantly　reduce　the　LGP　thickness.　The　design　process　and　optical　conditions　of　the　TLCS　are　first　discussed,　and　the　effect　of　structural　parameters　on　the　coupling　efficiency　is　also　analyzed.　After　that,　a　fundamental　model　and　an　improved　model　are　designed:　namely,　the　planar　TLCS　and　the　curved　TLCS.　Design　results　show　that　the　light　coupling　efficiency　of　the　proposed　TLCS　can　reach　95%,　while　the　LGP　thickness　is　reduced　to　7%　thinner　than　the　luminescence　regional　width　of　the　LED　source.　The　proposed　TLCS　will　have　broad　applications　in　light　guiding　devices.　(C)　2019　Optical　Society　of　America