The Tunability Of The Gh Shift Of The Light Reflected Fromcolloidal Ferrofluids

Goos-H?nche n Shift pla ys an very important role in the fie ld such as,optoelectronic device,near field measureme nt,optica l communicat ion,and so on.GH shift has been one of t he hot issues in the p hotostatic field s ince it been found by Goos and H?nche n in t he experime nt,There is a achieved pro mine nt research in the Goos-H?nche n Shift,such as,the enhance ment GH shift,negat ive GH shift and the influe nce of t he absorptio n to the GH s hift.But t he work for the t unab ilit y o f the Goos-H?nche n Shift is very less.However,it is k nown t hat t he tunability o f t he Goos-H?nchen Shift is intr insica lly important for the app licatio ns in optica l devices,the princ iple,to control the lateral shift in a fixed configurat ion or device by externa l fie ld.For examp le,the magnet ic fie ld applied e lectric fie ld,temperature and pressure,so as to realize the act ive contro l of latera l disp laceme nt.Under this theory,We selectcollo idal ferrofluidsa new t ype of functio na l materia l,we have adopted the stat ionary-phase theory to the ana lys is of the GH s hift o f a light beam re flected fro m t he collo idal ferrofluids.Collo idal ferrofluids are collo ida l suspens ions composed of ferroma gnet ic or ferr imagnet ic nanopartic les of dia meter dispersed in a carrier fluid and the typ ical carr ier fluid is water or kerosene.The ferromagnet ic fluid is a specia l kind of new funct iona l materia ls whic h having both magnet is m and fluid it y.The suspended nano-partic les of this mater ia l are easily controlled by the externa l applied ma gnet ic fie ld.Thereby the viscosity and structura l properties of this materia l can be altered significa nt ly.So that we can contro l the GH ferrofluid materia ls.In this paper,we will discuss fro m two part:ma gneto-contro l and structure-control.From the exper imenta l data we can find that the minimum reflect ivit y and d ielectr ic loss will increase when the increasing o f the loca l He factor,but both of the m are sma ll,the minimum reflectivit y less than one percent.It shows that the collo idal ferro fluids keeps the die lectric behavior.The abso lute value of t he GH s hift decreases as the increasing local factor,and the resonant angle of GH shift mo ves to lar ger incide nt angle and the widt h of GH shift become more widt h.When the vo lume factor p increasing,the collo ida l ferrofluids still have t he die lectr ic behavior whe n the p is s mall,a nd exhib it the metallic beha vior and the d ie lectric loss is very large when t he p is large va lue.However,the GH shift is st ill have a certain regularity that t he absolute value of the GH shift decreases as the increasing of t he p,and the minimum reflect ivit y of GH shift increase and the width of GH shift become more widt h.we conc lude that the GH shift of the collo idal ferrofluids have tenab ilit y.In this paper,we still d iscuss t hat the effects of t he comb inat io n of t he vo lume factor p and the local factor on t he GH shift.It shows t hat,the dependence of t he GH shift on the vo lume factor p for different loca l factor is that the absolute value of the GH shift will increase at first and then it will decrease at last as the increasing vo lume factor p.The dependences of t he GH shift on t he loca l factor for d ifferent vo lume factor p is that,for sma ller vo lume factor p,the curve for the GH s hift beco mes very anoma lous,for sma ller wave lengt h,the GH shift exhib its funnel shaped and it is not monotone cha nging wit h the increasing loca l factor;for larger wave le ngt h,the absolute va lue of the GH shift is a monotone increasing funct io n with t he increasing local factor.