Based　on　a　compact　electro-opto-thermal　model,　thermally　induced　current　bifurcation　and　drastically　collapse　of　output　optical　power　in　vertical　cavity　surface　emitting　laser　(VCSEL)　arrays　are　studied.　Taking　a　VCSEL　array　with　two　cells　for　example,　the　phenomenon　of　the　current　bifurcation　and　the　behavior　around　the　bifurcation　point　is　studied　and　substantiated　by　experiments　and　simulations.　With　the　aid　of　the　electro-opto-thermal　equivalent　circuit　of　VCSEL　arrays,　the　impact　of　series　resistance　and　cell　spacing　on　current　bifurcation　is　investigated　with　respect　to　the　temperature　dependencies　of　bias　current　and　output　optical　power.　Additional　ballasting　resistance　is　helpful　to　eliminate　current　bifurcation　at　an　expense　of　increasing　the　total　quadratic　power　dissipation.　Increasing　cell　spacing　is　helpful　to　alleviate　thermal　coupling　effect　and　delay　the　current　bifurcation.　VCSEL　arrays　with　proper　design　of　additional　ballasting　resistance　and　increasing　cell　spacing　can　alleviate　thermally　induced　current　bifurcation　and　hence　improve　the　total　output　optical　power.