The　explosive　market　growth　of　consumer　electronic　devices　has　made　a　great　demand　for　the　precise　processing　of　sapphire　by　using　ultrafast　lasers.　Ultrafast　lasers　can　induce　nonlinear　multiphoton　absorption,　and　thereby　leads　to　the　precise　and　defined　microfabrication　inside　transparent　materials　with　minimum　heating　effects.　The　induction　of　these　structural　modifications　by　tightly　focused　high　intensity　laser　pulses　is　a　versatile　technique　for　the　fabrication　of　three-dimensional　photonic　devices.　Ultrafast　lasers　are　therefore　widely　used　for　fundamental　research　as　well　as　practical　applications.　This　paper　presents　the　laser　induced　damage　mechanisms　and　absorption　phenomena　that　lead　to　structural　modifications　in　sapphire.　For　the　given　parameters,　the　electron　density　growth　as　a　result　of　plasma　generation　through　multiphoton　and　avalanche　processes　is　predicted　theoretically　and　is　found　to　be　greater　than　the　critical　electron　density　required　to　induce　breakdown　in　sapphire.　Structural　modifications,　from　small　change　of　refractive　index　to　birefringence,　cracks　and　voids　are　observed　when　sapphire　was　irradiated　experimentally　under　the　same　parameters.　Observations　revealed　the　creation　of　a　highly　crack　region　at　the　focal　volume　surrounded　by　local　refractive　index　change　which　enhances　in　radial　as　well　as　longitudinal　direction　with　increase　in　the　incident　laser　power　and　pulse　number.　Followed　by　this　highly　crack　region,　a　birefringent　region　associated　with　the　nonlinear　propagation　of　laser　beam　is　observed,　length　of　which　increases　with　increasing　input　power　however　no　significant　effect　is　observed　with　changing　number　of　pulses.　Depending　on　the　input　beam　powers,　this　region　has　length　of　several　hundred-micron　and　diameter　smaller　than　two　microns.