Op to Electronics 2003
-
Author
wintermute-gibson -
Category
Documents
-
view
447 -
download
0
Embed Size (px)
Transcript of Op to Electronics 2003
2003
- E = hv = Maxwell
hc
h = 6,626 10 34 J S
P : E hv h P c = f = = c c
E = P c
Maxwell
= E x B
(1)1
Edl =
d B dt
FARADAY
dt c dt. xy dB. ac dt dB=Bac dt
. , . c.
2
d B = Bac dt
gh
3
Edl = EaE = cB
1 2 3 Ea = Bac
Faraday
(2)1
Bdl = 0 0
d E dt
Ampere
dt xz E ac dt . , dE=Eac dt.
2
d E = Eac dt
gh
3
Bdl = BaB = 0 0 Ec Ampere
1 2 3 Ba = 0 0 Eac / /
Faraday & Ampere
E = cB
0 0 cE = B
c=
1
0 0
3,00 10 8 m / s
+x
B = Bmax (k )sin (t kx ) E max = cBmax x . t = 0. E xB. x.
E = E max ( j )sin (t kx )
E = y+ B= z+
E = y B= z
-x
B = Bmax (k )sin (t + kx ) E max = cBmax t = 0 , x. x.
E = E max ( j )sin (t + kx )
E = y+ B= z
E = y B= z+
E B
1
u=
1 1 0E2 + B2 2 2 0
2
B=
E = 0 0 E c
1 2 u = 0E2dU = udV = 0 E 2 ( Ac dt ) dt . u Ac dt dt
(
)
1 dU S = = 0 cE 2 A dt S=
0 0 2 EB E2 = E = 0 0 0 01J s m2 S 1 W m2
Poynting- Poynting: S =1
0
EB
:
S=
EB
0
( P) :
P = S dA
Poynting S (W/m2) .
S=
E B
0
=
Emax Bmax
0
sin2 (t kx) =
Emax Bmax [1 cos2(t kx)] 20
E B Sav = max max 20 E2max 1 0 2 1 E max = 0cE2max = I = Sav = 20c 2 0 2
cos2(t-kx) ( )
: cE = B E = cB( Faraday) ( Ampere)
B = E
B = 0 0 cE
= k m 0 , k m =1
1 k
=
1 kk m
1
00= c k
=
c kk m
k m = 1
=
=
1
0 0c
k > 1,
u1 0 < c = 0 n c = f n=
2
1
=
n2 n1
n1 n2
1
2
(2)
(a) ( ) (b) (a) . (c) , .
(a) (b)
1. 2. r = a
= 0 a, b :
sin a nb = na sin a = nb sin b sin b na
Snell
nb > na b < a nb < na b > a
(a) . (b) .
- FERMAT: FERMAT: ( ) s1, s2, s3, ,sm n1, n2, n3, ,nm :
1 m t = = ni si c i =1 i =1 i sim
: FERMAT :
n si =1
m
i i
FRESNEL E0i, E0r E0t , , :
E r 0 r E 0i
n cos i nt cos t = i ni cos i + nt cos t
E 2ni cos i t 0 t = E ni cos i + nt cos t 0i E n cos i ni cos t r || 0 r = t E 0i || ni cos t + nt cos i E 2ni cos i t || 0t = E 0i || ni cos t + nt cos i
.. R T
E R = 0r E 0i
= r2 E 0t E 0i n cos t = t n cos i i2
2
n cos t T= t ni cos i
2 t
na > nb Snell : sin b = na > 1, b > a nb a = crit sin b = 1 na sin a nb
b = 900
sin crit =
nb na
crit = 41.10 crit = 24.40
(a) . , 900, . 1,2 3 , . (b) ( ). , -
: (Evanescent) . . (Evanescent) 1/e
, , .
(a) . (b) , LASER , , , .
:
HUYGENS (1) . ().
r = t
HUYGENS (2)
OPA=AQO r=a
Huygens .
(a) . (b) (a)
AQO : AOB :
sin a =
at
AO t sin b = b AO
sin a a = = (Snell) sin b b
c c
b a
=
nb na
(a) . (b) (a). uba, n>>m, k.
- (2) n100MHz m,k10MHz
-- , . , , . , : (stable resonator) . (unstable resonator) . :
0 g1 g 2 1
gn = 1
L Rn
Rn .
Maxwell ( , ) laser (Transversal Electric Modes). / , . , . . : . x, y :
U mk ( x, y ) = H m H k exp (x2+ y2) L Hm, Hk
Gaussian (0,0) U00(x,y) gaussian :
U 00 ( x, y ) = exp (x2+ y2) L
L w= 2
1/ 2
2z w( z ) = w1 + L
1/ 2
w(z) , w (minimal beam waste).
(divergence) laser , :
=
2 nw
n .
Laser c- Q laser : : laser. : laser. laser (LiNbO3) - (, ). . : . . () n laser : c , L d ca nL E . c = = E c = c dt nL ca n. laser Q, :
Q=
EP
=
EdE dt
= c
P E .
Q (1) ( ns ns) () Q (Q-switching). Q laser laser . , , . Q, , . F N :
N dF = F 1 N dt t
dN N = 2F dt Nt
t laser. , i, .
Q (2) Q, , : - (Pockels shells) (fast rotating galvanometric mirrors-30000rpm) ( BDN) - (LiNbO3 crystals)
(1) (mode locking) ( ps) (Gwatts.) ( n+1-n=c/2L) laser . n n, central. , =2L/c. 1/, . :
E( t ) = En exp i(( 0 + n )t + f n ) ( N/n