The　smile　effect,　which　happens　when　various　light-emitting　units　convert　vertical　offsets　into　angular　offsets　following　fast-axis　alignment,　is　an　unavoidable　part　of　the　packaging　process　for　diode　laser　arrays　and　has　a　detrimental　influence　on　the　feedback　locking　of　external　cavity　diode　lasers.　The　external　cavity　spectral　beam　combining　system　without　output　coupler,　which　employs　the　0th　order　diffracted　light　with　low　grating　energy　to　enable　feedback　locking　of　the　light-emitting　unit,　is　particularly　severely　impacted　by　the　grin　effect.　The　external　cavity　spectral　beam　combining　system　without　output　coupler　uses　three　different　types　of　corrective　structures　to　simulate　and　explain　the　grin　effect　in　various　ways.　The　results　show　that　while　also　ensuring　adequate　feedback　and　better　combined　beam　quality,　the　double　-　separated　fast-axis　collimator　can　significantly　correct　the　smile　effect-induced　beam　shift.　However,　some　light-emittin　g　units＇　output　beams　cannot　be　corrected　for　the　S-shaped　smile　effect　with　complex　position　offset　changes;　The　fast-axis　telescope　system　can　effectively　offset　the　inadequate　feedback　brought　on　by　the　various　types　of　grin　effect,　but　it　is　unable　to　enhance　the　beam　quality　of　the　combined　beam　spot,　which　degrades　as　the　degree　of　smile　effect　increases;　The　combination　of　double-separated　fast-axis　collimator　and　fast-axis　telescope　system　can　complement　each　other　to　ensure　sufficient　feedback　for　different　forms　of　smile　effect　to　achieve　stable　wavelength　locking　and　better　beam　quality　of　the　combined　spot.　©　2023　SPIE.