1.55 µm X ê s; c" e P-p-n-N GaAs/AlGaAs üV ê s ì Å ºM 8 ý Ò ãÆ W ¥ üV ê s ì Å º Ç ù o Ú
_
@* å ? ∗ · b 9 * å * > · »` 9 Ú
ô
Dz D G õ < Æl Õ ü t ½ ¨" é ¶ F g l Õ ü t ½ ¨G ' p , " fÖ ¦ 136-791 (2004¸ 8 Z 4 11{ 9 ~ à Î6 £ §)
é
ß { 9 ¸× ¼ GaAs/AlGaAs ridge ¸ Ð 0 A © ¸l MOCVD (metal organic chemical vapor depo- sition) $ í © l Z O õ o < Æ& h _ þ vd d y ~ ½ ÓZ O ` ¦ s 6 x # ] j ÷ &% 3 . P-p-n-N s × æ_ s 7 á x] X ½ + Ë(double heterostructure) 0 A © ¸l _ 0 A © ¸ : £ ¤$ í É r % i s # QÛ ¼ · ú ` ¦ or v " f Mach-Zehnder ç
ß
[ O ~ ½ ÓZ O ` ¦ s 6 x # 1.55 µm © \ " f 8 £ ¤& ñ ÷ &% 3 . TE ¼ # F g \ " f 8 £ ¤& ñ ) a Û ¼0 Ag A · ú É r 2.2 ^ ¦ à
Ôs ¦ 0 A © ¸ ´ òÖ ¦ É r 40.9
◦/V ·mm Ð Z } > % 3 # Q& . s 0 A © ¸ ´ òÖ ¦ É r 1.55 µm © \ " f GaAs/AlGaAs ü < InGaAsP/InP 0 A © ¸l [ þ t \ " f Ð ¦ ) a © H z ´+ « > ° ú כs .
PACS numbers: 42
Keywords: P-p-n-N ¸ Ð 0 A © ¸l , GaAs/AlGaAs ridge ¸ Ð, Mach-Zehnder ç ß [ O > , 0 A © ¸ ´ òÖ ¦
I. " e  ] Ø
GaAs ü < InP\ ¦ l ì ø ÍÜ ¼ Ð H III-V7 á ¤ o½ + ËÓ ü t ì ø Í ¸
^
\ ¦ s 6 xô Ç 0 A © ¸l H F g " é ¶ ¢ ¸ H F g Ø ¦ l ü < é ß { 9
| 9 & h s 6 x s ½ + É ÷ rë ß m , ± ú É r · ú õ Â ú ª É r F
GU ´s \ " f ¸ H 0 A © ¸ % 3 # Q . ¢ ¸ô Ç s 0 A ©
¸l Mach-Zehnder (MZ) ç ß [ O l ~ ½ Ó ¾ Ó$ í ½ + Ë l
(directional coupler) ½ ¨ ¸ü < ½ + Ë÷ & ; ¤ ¸ F g Û
¼0 Ag As % 3 # Q . " f F g ¸l [ þ t × æ \ " f 0 A ©
¸l H ¦5 Å q F g: x õ F g ñ % o r Û ¼% 7 ` ¦ % 3 l 0 Aô Ç
×
æ כ ¹ô Ç ü @Â Ò ¸l s .
þ
j H \ GaAs/AlGaAs [1–4]ü < InGaAsP/InP [5, 6] s 7
á
x] X ½ + Ë ½ ¨ ¸[ þ t` ¦ s 6 xô Ç 0 A © ¸l [ þ t s µ 1 ϳ ð÷ &% 3 .
l © ´ òõ ü < Ä » î rì ø Í ´ òõ \ ¦ ¸¿ º s 6 x ½ + É Ã º e
¦, l > r_ P-n-N ½ ¨ ¸ Ð ¸ F g õ ) a l © _
g Ë >s 7 £ x H P-p-n-N GaAs/AlGaAs 0 A © ¸l \
"
f Ð ¦ ) a TE 0 ¸× ¼_ 0 A © ¸ ´ òÖ ¦ É r 1.06 µm ü < 1.31 µm © \ " f y y 96 ◦ /V ·mmü < 54.9 ◦ /V ·mm Ð µ 1 ϳ ð÷ &
%
3 [1–4]. ¢ ¸ P-P-p-i-n-N-N GaAs/AlGaAs W- F g ¸
Ð 0 A © ¸l H 1.31 µm © \ " f 0 A © ¸ ´ òÖ ¦ õ
< Hz ´s y y 34.6 ◦ /V ·mm ü < 0.2 ∼ 0.6 dB/cm Ð & ³F
t © a % ~ É r : £ ¤$ í ` ¦ ? / ¦ e [3].
ô
Ǽ # 1 l x © s 1.50 ∼ 1.55 µm % ò % i \ e ` ¦ M : GaAs ü < InP l ì ø Í_ 0 A © ¸l \ " f 0 A © ¸ ´ òÖ ¦ É r t
F K t _ Ð ¦÷ &# Q e t · ú § . 1.53 µmü < 1.52
∗
E-mail: [email protected]
µm © \ " f Ð ¦ ) a TE 0 ¸× ¼_ 0 A © ¸ ´ òÖ ¦ É r P- n-N õ P-I-i-I-N GaAs/AlGaAs 0 A © ¸l \ " f y y 27 ◦ /V ·mmü < 2.9 ◦ /V ·mm s % 3 [7,8]. ¢ ¸ô Ç 1.55 µm
© \ " f s : r& h Ü ¼ Ð > í ß ) a P-p-n-N GaAs/AlGaAs 0 A ©
¸l _ 0 A © ¸ ´ òÖ ¦ s µ 1 ϳ ð÷ &% 3 [9]. 1.50 ∼ 1.55 µm © % ò % i \ " f à Р¦ë H ³ 7õ 9_ õ q §÷ & P- n-N ½ ¨ ¸_ 0 A © ¸ ´ òÖ ¦(27 ◦ /V ·mm)s P-p-n-N ½ ¨ ¸ _
0 A © ¸ ´ òÖ ¦(24.9 ◦ /V ·mm) Ð 8 H כ ` ¦ · ú Ã º e
. s õ H G. Mendoza-Alvarez [1] 1.06 µm ©
\
" f z ´+ « >õ s : r& h ì r$ 3 Ü ¼ Ð % 3 É r õ 0 A © ¸
´
òÖ ¦ É r P-n-N ½ ¨ ¸\ " f Ð P-p-n-N ½ ¨ ¸\ " f 2C
&
ñ ¸ t ¾ Ó © ) a H z ´õ { 9 u t · ú § H . Õ ªo ¦ 1
l
x © s 1.50 ∼ 1.55 µm % ò % i \ e ` ¦ M : GaAs l ì ø Í _
0 A © ¸l _ z ´+ « > õ [ þ t s _ Ð ¦÷ &t · ú § ¤ .
:
£
¤ y , P-p-n-N GaAs/AlGaAs 0 A © ¸l \ " f 0 A ©
¸ : £ ¤$ í \ @ /ô Ç ½ ¨ õ H f t µ 1 ϳ ð÷ &t · ú § ¤ .
" f 1.55 µm © \ " f à Р¦ë H ³ 1õ 9_ õ × æ # Q Ö
¼ כ s z ´+ « >& h Ü ¼ Ð ´ ú H t \ ¦ S X ½ + É Ã º \ O .
: r 7 Hë H \ " f H 1 l x © s 1.55 µm{ 9 M : P-p-n-N GaAs/AlGaAs s × æ_ s 7 á x] X ½ + Ë(Double Heterostruc- ture; DH) ¸ Ð 0 A © ¸l _ 0 A © ¸ ´ òÖ ¦ s MZ ç
ß [ O ~ ½ ÓZ O ` ¦ s 6 x # % i s # QÛ ¼ · ú _ < ÊÃ º Ð TE ¼ # F
g \ " f % 6 £ § Ü ¼ Ð ½ ¨÷ &% 3 . 1.55 µm © \ " f 8 £ ¤& ñ ) a 0
A © ¸ ´ òÖ ¦ É r P-n-N ½ ¨ ¸\ " f Ð ¦ ) a ° ú כ [7] Ð ß ¼l M
:ë H \ P-p-n-N ½ ¨ ¸\ " f 0 A © ¸ ´ òÖ ¦ s ¾ Ó © H d` ¦ · ú Ã
º e . s כ É r 1.06 µm © \ " f Ð ¦ ) a G. Mendoza- Alvarez_ õ [1]ü < { 9 u ô Ç .
-406-
Fig. 1. Epitaxial structure and refractive index profile of P-p-n-N GaAs/AlGaAs phase modulators.
II. üV ê s ì Å ºM < gX c l
0
A © ¸ ´ òÖ ¦ s H 0 A © ¸l \ ¦ ] j l 0 AK " f H ì
ø Í ¸^ ¸ Ð\ " f % 3 ` ¦ à º e H 0 A © ¸[ þ t s ¸¿ º s 6
x ÷ &# Q ô Ç . 0 A © ¸l \ " f Ï ã J] X Ò ¦_ 8 ú x o H l
© ´ òõ (1 x 9 2 l F g < Æ ´ òõ )ü < Ä » î rì ø Í ´ ò õ [ þ t (e ¦ Ý ¼ ü < { G ¹ ¡ § ´ òõ )_ ½ + Ës . " f Ï ã J] X Ò
¦ o\ ¦ Å Ò H l © ´ òõ ü < Ä » î rì ø Í ´ òõ \ ¦ ¸
¿
º s 6 x½ + É Ã º e H 0 A © ¸l _ ½ ¨ ¸ H ¸ Ð8 £ x s ¸ i ç
÷ & ¦, ¸ ¸× ¼ü < ) a l © _ g Ë >s 7 £ x ¸ 2
¤ p-n ] X ½ + Ës ¸ Ð8 £ x × æç ß \ ë ß [ þ t # Q4 R ô Ç . 7 £ ¤ ¸
Ð 0 A © ¸l H P- ü < N-AlGaAs 9 þ t A ` ç 8 £ x[ þ t s \ p- ü < n-GaAs ¸ Ð8 £ x s ¶ ú { 9 ) a P-p-n-N ½ ¨ ¸\ ¦ 4 R ô
Ç [4].
Fig. 1 É r P-p-n-N GaAs/AlGaAs DH 0 A © ¸l _ \ x
~ à Ì} ½ ¨ ¸ü < Ï ã J] X Ò ¦ ì r ís . \ x ~ à Ì} ½ ¨ ¸ H (100)
~
½ Ó ¾ Ó_ n + -GaAs l ó ø Í 0 A\ MOCVD (metal organic chemical vapor deposition) l Z O Ü ¼ Ð $ í © ÷ &% 3 . \ x
~ Ã
Ì} 8 £ x[ þ t É r n + -GaAs l ó ø Í 0 A\ 3.5 µm N-Al 0.4 Ga 0.6 As
A A á ¤ 9 þ t A ` ç 8 £ x, 0.125 µm n-GaAs ¸ Ð 8 £ x, 0.125 µm p-GaAs ¸ Ð8 £ x, 1.5 µm P-Al 0.4 Ga 0.6 As 0 AA á ¤ 9 þ t A
` ç 8 £ x, Õ ªo ¦ 0.2 µm p + -GaAs F G8 £ x (cap layer) Ü ¼
Ð ½ ¨$ í ) a . \ x ~ Ã Ì} _ ¸i ç 0 l x ¸ H N-Al 0.4 Ga 0.6 As ü <
P-Al 0.4 Ga 0.6 As 9 þ t A ` ç 8 £ x[ þ t s 3 × 10 17 cm −3 s ¦, n- GaAs ü < p-GaAs ¸ Ð8 £ x[ þ t É r 5 × 10 17 cm −3 s % 3 .
¢
¸ p + -GaAs F G 8 £ x_ ¸i ç 0 l x ¸ H 2 × 10 18 cm −3 s
%
3 . Si õ C dopant[ þ t s n(N)- õ p(P)-+ þ A GaAsü <
Al 0.4 Ga 0.6 As \ y y 6 x ÷ &% 3 Ü ¼ 9, ¸ H ¸i ç É r \ x ~ Ã Ì }
` ¦ $ í © ½ + É M : ë ß [ þ t # Q& .
Ridge ¸ Ð ½ ¨ ¸ H _ þ vd d y ~ ½ ÓZ O ` ¦ s 6 x # ] j
÷
&% 3 . TE 0 ¸× ¼\ @ /K [011] ~ ½ Ó ¾ Ó\ " f LEO (linear
Fig. 2. Scanning electron micrograph showing the cleaved end-face of the P-p-n-N ridge waveguide phase modulator.
electro-optic) ´ òõ H Ä » î rì ø Í ´ òõ \ 8K t l M : ë
H \ F g ¸ Ð H í Ðo èÕ ª x ü < _ þ vd d y ~ ½ ÓZ O ` ¦ s 6
x # [011]~ ½ Ó ¾ ÓÜ ¼ Ð ] j ÷ &% 3 . d y Û ¼ß ¼ H í ÐY U t
Û ¼à Ô (AZ1450J) J Ü ¼ Ð ë ß [ þ t # Q & Ü ¼ 9, d y É r 30ì r 1
l
xî ß ¸ ú B$ 3 ) a H 3 PO 4 : H 2 O 2 : H 2 O (19 % : 6 % : 75
%) 6 xÓ os 6 x ÷ &% 3 [3,4].
F G` ¦ ë ß [ þ t l 0 AK d y ) a r « Ñ [ j' ) a Ê ê poly- imide Û ¼ 2 ; ïh A÷ & ¦ â o÷ &% 3 [3–6]. Õ ªo ¦ RIE
© q \ ¦ 6 x # ridge ¸ Ð_ cap layer ¸Ø ¦ ÷ & ¸2 ¤ polyimide H O 2 e ¦ Ý ¼ Ð d y ÷ &% 3 . P-type ohmic
F G` ¦ ë ß [ þ t l 0 AK " f e-beam 7 £ x à Ìl \ ¦ s 6 x # p + - GaAs ü < polyimide 0 A\ Au:Zn/Au 7 £ x à Ì÷ &% 3 . ô Ǽ # 0
A © ¸l _ ª A á ¤ = å Q` ¦ ] X é ß ½ + É M : Ö ¦ ` ¦ ~ 1 > % 3 l 0 AK " f r « Ñ_ ¿ ºa 100 µm ÷ & ¸2 ¤ n + -GaAs l ó ø Í _ A A á ¤ s ÷ &% 3 . 6 £ § É r N-type ohmic F G` ¦ 0 AK ) a n + -GaAs l ó ø Í 0 A\ Au:Ge/Ni/Au 7 £ x à Ì
÷
&% 3 . t } Ü ¼ Ð ohmic F G` ¦ ¢ - a$ í l 0 AK r « Ñ
H RTA (rapid thermal annealing) © q \ ¦ s 6 x # 410
◦ C \ " f 30 í 1 l xî ß \ P % o ÷ &% 3 . Õ ªo ¦ 0 A © ¸l H U
´s 2 mm ÷ & ¸2 ¤ ] X é ß ) a Ê ê Au ¸F K ) a î r à Ô 0 A\ silver paste Ð ¦& ñ ÷ &% 3 .
Fig. 2 H ] j ) a P-p-n-N GaAs/AlGaAs ridge ¸
Ð 0 A © ¸l _ é ß ` ¦ n É r SEM (scanning electron mocroscope) s . _ þ vd d y 6 xÓ o\ _ K 1 p x~ ½ Ó$ í d y
(isotropic etching)s ÷ &l M :ë H \ ridge ¸ Ð\ " f 0 A A
á
¤ ; ¤ õ A A á ¤_ ; ¤ É r y y 0.8 µmü < 3.6 µm ÷ &% 3 .
s
M : d y U ·s 1.9 µms l M :ë H \ ridge ¸ Ð H p-GaAs ü < n-GaAs_ â > Ð 8 U ·s d y ÷ &# Q e 6
£
§` ¦ · ú Ã º e .
Fig. 3. Mach-Zehnder interferometer setup to measure the phase shifts as a function of the reverse applied bias voltage.
III. üV ê s ì Å º ¤X N Ë
0
A © ¸l _ 0 A © ¸ ´ òÖ ¦ É r Mach-Zehnder (MZ) ç
ß [ O l Fabry-Perot (FP) ç ß [ O l \ ¦ s 6 x # 8 £ ¤& ñ | ¨ c Ã
º e . FP / B N" î ~ ½ ÓZ O [3] É r 0 A © ¸l é ß _ ì ø Í Ö ¦
`
¦ · ú 0 A © ¸ ´ òÖ ¦ õ F g < Hz ´` ¦ ô Ç _ z ´+ « >\ " f 8 £ ¤
&
ñ ½ + É Ã º e H © & h s e . Õ ª Q FP ~ ½ ÓZ O É r F g < Hz ´s
H ¸ Ð\ " f F g < Hz ´ 8 £ ¤& ñ s # Q§ > ¦, 0 A © ¸l \ " f Û
¼0 Ag A · ú _ 8 £ ¤& ñ É r 0 p x t ë ß ) a · ú \ @ /6 £ x
÷
& H 0 A © o\ ¦ 8 £ ¤& ñ ½ + É Ã º \ O H é ß & h s e . Õ ª QÙ ¼ Ð
: r 7 Hë H \ " f H y y _ ) a % i s # QÛ ¼ · ú \ " f 0 A
© o(phase shift)` ¦ 8 £ ¤& ñ l 0 AK MZ ç ß [ O ~ ½ ÓZ O s s 6
x ÷ &% 3 .
Fig. 3 É r 0 A © ¸ ´ òÖ ¦` ¦ 8 £ ¤& ñ l 0 Aô Ç MZ ç ß [ O ~ ½ Ó Z O
_ 8 £ ¤& ñ © u ¸ s . MZ ç ß [ O l _ ô ÇA á ¤ (arm)\ Z
~ # 0 A © ¸l \ " f » ¡ ¤& h ) a 0 A © o 8 £ ¤& ñ ÷ &% 3
. ç ß [ O Á º] ( 8 £ ¤& ñ ÷ & H 1 l xî ß \ 0 A © s ; ;s H
כ
s ' a8 £ ¤ ÷ &l M :ë H \ s \ ¦ ] j l 0 AK " f F g _ s ^ ¦ 0 A\ e H ^ z ´+ « > © u [ þ t É r ß ¼w n = © 5 Å q \ Z ~ # &
. 1.55 µm DFB Y Us $ _ Ø ¦§ 4 F g É r NA 0.45_ @ /Ó ü t E $
Ý ¼\ _ K ¸ Ð_ { 9 \ end-fire coupling ÷ & ¦, 0
A © ¸l _ Ø ¦§ 4 F g É r ° ú É r C Ö ¦_ E $ Ý ¼ Ð S X @ /÷ &% 3
. { 9 F g_ ¼ # F g © I H ' Í P : F gì r o l · ú ¡\ Z ~ #
¼ #
F g l \ _ K ¸] X ÷ &% 3 . ç ß [ O Á º] ( H l ï r (refer- ence arm) õ 0 A © ¸l Z ~ # ¸ Ð (waveguide arm)` ¦ H ¿ º > h_ c [ þ t_ 0 Au { 9 u | ¨ c M : ë ß [ þ t
#
Q . ç ß [ O Á º] ([ þ t É r Hamamatsu C1000 B j \ _ K
Ø ¦ ÷ &# Q TV ¸m ' \ © s è ß . " f Ð É r
`
¦ : x õ H c [ þ t_ F g â Ð (optical pass difference)ü <
Fig. 4. Interference fringe patterns of the TE 0 mode measured as a function of the reverse bias voltage varying from 0 to -5V.
F
g [ jl ¸] X H d Ü ¼ Ð" f a % ~ É r y © ¸ @ /q (intensity con- trast)\ ¦ ° ú H ç ß [ O Á º] ( % 3 # Q .
$ ] j ) a 0 A © ¸l é ß { 9 ¸× ¼ë ß ¸ r v H כ
`
¦ ¸ l 0 AK near-field ì r í ¸ ÷ &% 3 . s \ ¦ 0 A K
Fig. 3\ " f A A á ¤ l ï r ` ¦ : x õ H F g s é ß ÷ &
%
3 . Õ ªo ¦ 0 A © ¸l Z ~ # ¸ Ð ` ¦ : x õ
H F g` ¦ s 6 x # ' a8 £ ¤ ) a near-field J Ü ¼ ÐÂ Ò' ¸
Ð\ { 9 ) a F g_ ¦ ¸× ¼[ þ t s # l ÷ &t · ú § H כ s S X
÷ &% 3 . " f ] j ) a ridge ¸ Ð 0 A © ¸l H é ß { 9
¸× ¼ë ß ¸ r .
ç
ß [ O Á º] (_ s 1 l x É r ridge ¸ Ð U ´s 2 mm 0 A
© ¸l \ ) a % i s # QÛ ¼ · ú _ < ÊÃ º Ð 8 £ ¤& ñ ÷ &
%
3 [1,2,4]. Fig. 4 H ] j ) a 0 A © ¸l \ " f % i s
#
QÛ ¼ · ú s 0 V\ " f -5 V t -1.0 V_ ç ß Ü ¼ Ð 8 £ ¤& ñ
)
a TE 0 ¸× ¼_ ç ß [ O Á º] ( s 1 l x` ¦ Ð# ï r . Õ ªa Ë >Ü ¼ ÐÂ Ò '
à ºf ` ¦ l ï r Ü ¼ Ð ^ ¦ M : % i s # QÛ ¼ · ú s 7 £ x < Ê
\
ç ß [ O Á º] (_ 0 A © s H כ s ~ 1 > ' a¹ 1 Ï ) a .
7
£
¤ ç ß [ O Á º] ( Ä º8 £ ¤ \ " f Ò' ý a8 £ ¤ Ü ¼ Ð s 1 l xô Ç .
Fig. 4 ÐÂ Ò' y y _ · ú \ " f 0 A © _ o| ¾ Ós 8
£
¤& ñ ) a Ê ê % i s # QÛ ¼ · ú _ < ÊÃ º Ð 0 A © o| ¾ Ós % 3
#
Q& . Fig. 5 H TE ü < TM ¼ # F g \ " f % i s # QÛ ¼ · ú _
< ÊÃ º Ð 8 £ ¤& ñ ) a 0 A © os . 0 A © s 180 ◦ ë ß p u ½ + É M
: 9 כ ¹ô Ç · ú s Û ¼0 Ag A · ú (V π ) s . x h A / B G Ü
¼ РÒ' TE 0 ¸× ¼_ Û ¼0 Ag A · ú É r -2.2Vs . ô Ǽ # ]
j ) a 0 A © ¸l \ " f 8 £ ¤& ñ ) a TE 0 ¸× ¼_ 0 A © s 180 ◦ ë
ß p u H X < 9 כ ¹ô Ç % i s # QÛ ¼ · ú É r Fig. 6 \ " f Ð
Fig. 5. Phase shift of the TE 0 and TM 0 mode measured as a function of the reverse bias voltage at the phase modulator.
Fig. 6. Switching voltage(V π ) necessary to obtain the phase shift of 180 ◦ at the phase modulator.
#
. s Õ ªa Ë >Ü ¼ ÐÂ Ò' 1.55 µm © \ " f 0 A © ¸l _ Û ¼0 Ag A · ú s - 2.2 V Ð ± ú 6 £ §` ¦ · ú Ã º e .
s
] j 0 A © ¸l _ Û ¼0 Ag A · ú (V π ) õ U ´s (L)\ ¦ · ú l
M :ë H \ U ´s 1mm ¸ Ð 0 A © ¸l \ 1V_
· ú s | ¨ c M :_ 0 A © o Ð & ñ _ ÷ & H 0 A © ¸ ´ ò Ö
¦( ◦ /V ·mm)s & ñ | ¨ c à º e . 0 A © ¸l _ U ´s H 2 mm s ¦ Fig. 5ü < Fig. 6Ü ¼ РÒ' · ú à º e 1 p w s 8 £ ¤& ñ
)
a Û ¼0 Ag A · ú s 2.2 Vs Ù ¼ Ð 1 l x © s 1.55 µm { 9 M
: TE 0 ¸× ¼\ " f 8 £ ¤& ñ ) a 0 A © ¸l _ 0 A © ¸ ´ òÖ ¦
É r 40.9 ◦ /V ·mm Ð ß ¼ . s ´ òÖ ¦ É r 1.55 µm © % ò % i
\
" f µ 1 ϳ ð ) a III-V o½ + ËÓ ü t ì ø Í ¸^ \ ¦ s 6 xô Ç 0 A © ¸l
×
æ \ " f © ß ¼ . ¢ ¸ô Ç s ´ òÖ ¦ É r 1.53 µm © \ " f µ 1 Ï
³
ð ) a P-n-N GaAs/AlGaAs 0 A © ¸l _ 0 A © ¸ ´ ò Ö
¦(27 ◦ /V ·mm) [7] Ð ß ¼l M :ë H \ 0 A © ¸ ´ òÖ ¦ s P- n-N ½ ¨ ¸\ " f Ð P-p-n-N ½ ¨ ¸\ " f 2C & ñ ¸ t ¾ Ó
© ) a ¦ µ 1 ϳ ðô Ç G. Mendoza-Alvarez [1] _ õ ü < { 9 u ô
Ç . Õ ª QÙ ¼ Ð A. Bandyopadhyay [9] 1.55 µm © \
"
f s : r& h Ü ¼ Ð > í ß # µ 1 ϳ ðô Ç P-p-n-N GaAs/AlGaAs 0
A © ¸l _ 0 A © ¸ ´ òÖ ¦ (24.9 ◦ /V ·mm) É r z ´+ « >° ú כõ
´
ú §s É r כ ` ¦ · ú Ã º e .
Fig. 5 РÒ' TM 0 ¸× ¼_ Û ¼0 Ag A · ú s 3.1 Vs l M
:ë H \ TM 0 ¸× ¼_ 0 A © ¸ ´ òÖ ¦ É r 29.0 ◦ /V ·mm s .
s
° ú כ É r TE 0 ¸× ¼_ 0 A © ¸ ´ òÖ ¦ Ð . Õ ª s Ä » H
\
x ~ Ã Ì} s [001] ~ ½ Ó ¾ ÓÜ ¼ Ð $ í © ÷ & ¦ ) a · ú _ ~ ½ Ó
¾
Ós [001] s l M :ë H \ TM ¼ # F g \ " f 1 l F g < Æ ´ òõ
\
_ ô Ç Ï ã J] X Ò ¦ o, 7 £ ¤ 0 A © o \ O l M :ë H s [4].
ô
Ǽ # à Р¦ë H ³ 9\ _ 1.55 µm\ " f TE 0 ¸× ¼_ é
ß 0 AU ´s { © 0 A © o(∆φ/L) H P-p-n-N InGaAsP/InP
¸l \ " f Ð P-p-n-N GaAs/AlGaAs ¸l \ " f 8 ß
¼ . Õ ª s Ä » H Ä » î rì ø Í \ _ ô Ç Ï ã J] X Ö ¦_ 8 ú x o
InGaAsP Ð GaAs\ " f 8 ß ¼l M :ë H s . ¢ ¸ GaAs_ LEO > Ã º InGaAsP_ ° ú כ Ð ç ß ß ¼l M :ë H \ LEO
´
òõ ü < Ä » î rì ø Í ´ òõ _ ½ + Ës InGaAsP\ " f 8 H QEO(quadratic electro-optic) ´ òõ Ð 8 ß ¼> ) a .
" f : r 7 Hë H \ " f [ O " î ) a P-p-n-N GaAs/AlGaAs 0 A ©
¸l _ 0 A © ¸ ´ òÖ ¦ (40.9 ◦ /V ·mm)s à Р¦ë H ³ 6\ " f µ
1 ϳ ð ) a P-p-n-N InGaAsP/InP 0 A © ¸l _ 0 A © ¸
´
òÖ ¦(34.6 ◦ /V ·mm) Ð 8 ß ¼> % 3 # Q כ s ¸ ú [ O " î ) a
.
t } Ü ¼ Ð Fig. 5\ " f % i s # QÛ ¼ · ú _ < ÊÃ º Ð 8 £ ¤
&
ñ ) a 0 A © o| ¾ Ó É r + þ A(linear)s m ¦ sublinear ) a
. s כ É r 6 £ § õ ° ú É r & ñ $ í & h ~ ½ ÓZ O Ü ¼ Ð s K | ¨ c à º e
. { 9 F g_ ~ ½ Ó ¾ Ós [011]{ 9 M : TE 0 ¸× ¼_ 0 A ©
o H LEO ´ òõ , QEO ´ òõ , PL´ òõ , Õ ªo ¦ BF ´ òõ \ _
ô Ç 0 A © o_ ½ + ËÜ ¼ Ð % 3 # Q . 1 l x © s ½ × ¼Ì s
© (λ g ) H % \ e ` ¦ M : LEO ´ òõ H % i s # QÛ ¼ · ú
\
q Y V ¦, QEO ´ òõ H √
3V b \ q Y Vô Ç . ¢ ¸ BFü < PL
´ òõ H √
V b \ q Y Vô Ç [1]. " f % i s # QÛ ¼ · ú \
@
/ô Ç QEO, PL, BF ´ òõ [ þ t \ _ ô Ç 0 A © o_ ½ + Ë É r H
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\ LEOü < PL ´ òõ _ o H t ë ß QEOü < BF
´
òõ H ß ¼> y èô Ç . : £ ¤ y , QEO ´ òõ _ y è BF ´ ò õ
_ y è Ð 8 ß ¼ . " f √
V b \ q Y V H BF ü <
PL ´ òõ \ _ ô Ç 0 A © o| ¾ Ós t C & h s l M :ë H \ © l 4 t ´ òõ _ ½ + Ë É r Fig. 5 % ! 3 sublinear H d` ¦ · ú Ã º e
.
t
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º < Hz ´ Ð ½ ¨$ í ) a [10]. 0 A © ¸l H ¾ ºØ ¦ < Hz ´` ¦ × ¦ s l
0 AK A A á ¤ 9 þ t A ` ç 8 £ x_ ¿ ºa 3.5 µm Ð ¿ º, ¦ · ú À
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à Р¦ë H ³ 10õ 1 l x{ 9 ô Ç _ þ vd d y ~ ½ ÓZ O s s 6 x ÷ &% 3 .
" f < Hz ´\ © H % ò ¾ Ó` ¦ p u H כ ¹ É r ¸
Ðü < 9 þ t A ` ç \ ¸i ç ) a Ä » î rì ø Í \ _ ô Ç f ¨ Ã º < Hz ´s
. Õ ª Q 0 A © ¸ ´ òÖ ¦ s ß ¼ 180 ◦ _ 0 A © o\ ¦ % 3 l
0 AK 9 כ ¹ô Ç 0 A © ¸l _ U ´s (L π ) t l M : ë
H \ 0 A © ¸l _ U ´s L π { 9 M : < Hz ´s
. : r 7 Hë H õ Ä » ô Ç \ x ~ Ã Ì} ½ ¨ ¸\ ¦ ° ú H 0 A © ¸ l
\ " f > í ß ) a TE 0 ¸× ¼_ f ¨ à º < Hz ´ É r à Р¦ë H ³ 1\ " f
Ð ¦÷ &# Q e . 7 £ ¤, 0 A © ¸l _ U ´s L π â Ä º 0 V ü
< Û ¼0 Ag A · ú (V π = 2V) \ " f © _ < ÊÃ º Ð > í ß ) a f ¨ Ã
º < Hz ´ É r © s 1.06 µm{ 9 M : y y 0.52ü < 0.7 dB ) a
. Õ ªo ¦ f ¨ à º < Hz ´ É r © s 7 £ x < Ê\ t à º < Êà º
&
h Ü ¼ Ð y è÷ & ¦ e l M :ë H \ 1 l x © s 1.55 µm{ 9 M : f
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IV. + s Ç Â ] Ø
1.55 µm © \ " f 1 l x H P-p-n-N GaAs/AlGaAs ridge ¸ Ð 0 A © ¸l _ 0 A © ¸ : £ ¤$ í s % 6 £ § Ü ¼ Ð [ O
" î ÷ &% 3 . 38 £ x_ @ /g A+ þ A GaAs/AlGaAs DH ridge ¸
Ð 0 A © ¸l H MOCVD $ í © l Z O õ _ þ vd d y ~ ½ ÓZ O Ü
¼ Ð ] j ÷ &% 3 Ü ¼ 9, F g_ ¸ : £ ¤$ í [ þ t s 1.55 µm © \
"
f 8 £ ¤& ñ ÷ &% 3 . Ridge 0 AA á ¤_ ; ¤ s 0.8 µm 0 A © ¸ l
H near-field 8 £ ¤& ñ Ü ¼ РÒ' é ß { 9 ¸× ¼ë ß # l ÷ & H כ s S X
÷ &% 3 . 0 A © ¸ : £ ¤$ í É r % i s # QÛ ¼ · ú ` ¦
" f MZ ç ß [ O ~ ½ ÓZ O ` ¦ s 6 x # 8 £ ¤& ñ ÷ &% 3 . TE 0 ¸
×
¼ü < TM 0 ¸× ¼_ 0 A © ¸ ´ òÖ ¦ É r y y 40.9 ◦ /V ·mmü <
29.0 ◦ /V ·mm Ð Z } > 8 £ ¤& ñ ÷ &% 3 . s ´ òÖ ¦ É r 1 l x © s 1.50 ∼ 1.55 µm { 9 M : GaAsü < InP l ì ø Í_ ì ø Í ¸^ 0 A ©
¸l \ " f µ 1 ϳ ð ) a 0 A © ¸´ òÖ ¦ [5–9] × æ \ " f © ß ¼
.
ô
Ǽ # : r 7 Hë H_ 0 A © ¸ ´ òÖ ¦ É r 1.55 µm © \
"
f 8 £ ¤& ñ ) a P-n-N ¸l _ ° ú כ [7] Ð ß ¼l M :ë H \ G. Mendoza-Alvarez_ õ ü < ¸ ú { 9 u ô Ç . " f A.
Bandyopadhyay [9]_ > í ß ° ú כ É r z ´] j 8 £ ¤& ñ ° ú כ Ð ± ú >
>
í ß ÷ &% 3 6 £ §` ¦ · ú à º e . Õ ªo ¦ 1.55 µm © \ " f P-p-n-N ¸i ç ½ ¨ ¸\ ¦ ° ú H GaAs/AlGaAs ¸l ü < In- GaAsP/InP ¸l \ " f TE 0 ¸× ¼_ 0 A © ¸ ´ òÖ ¦ É r
8 H s Ä » s : r& h Ü ¼ Ð [ O " î ÷ &% 3 .
Y c
p w à U Ø ô
[1] G. Mendoza-Alvarez, L. A. Coldren, A. Alping, R.
H. Yan, T. Hausken, K. Lee and K. Pedrotti, IEEE J. Lightwave Technol. LT-6, 793 (1988).
[2] S. S. Lee, R. V. Ramaswamy and V. S. Sundaram, IEEE J. Quantum Electron. 27, 726 (1991).
[3] Young Tae Byun, Kyung Hyun Park, Sun Ho Kim, Sang Sam Choi, Jong Chang Yi and Tong Kun Lim, Appl. Opt. 37, 496 (1998).
[4] Young Tae Byun, Young Min Jhon and Sun Ho Kim, Sae Mulli (The Korean Physical Society) 47, 253 (2003).
[5] Hwa Sun Park, Jong Chang Yi and Young Tae Byun, Sae Mulli (The Korean Physical Society) 45, 271 (2002).
[6] Hwa Sun Park, Jong Chang Yi, Young Tae Byun, Seok Lee, Sun Ho Kim, Mitsuru Takenaka and Yoshiaki Nakano, Jpn J. Appl. Phys. 42, 4378 (2003).
[7] A. Alping, X. S. WU and L. A. Coldren, Electron.
Lett. 23, 93 (1987).
[8] R. J. Deri, E. Kapon, J. P. Harbison, M. Seto, C.
P. Yun and L. T. Florez, J. Appl. Phys. 53, 1803 (1988).
[9] A. Bandyopadhyay and P. K. Basu, J. Lightwave Technol. 10, 1438 (1992).
[10] Young Tae Byun, Kyung Hyun Park, Sun Ho Kim,
Sang Sam Choi and Tong Kun Lim, Appl. Opt. 35,
928 (1996).
High Phase Modulation Efficiency of a P-p-n-N GaAs/AlGaAs Phase Modulator at 1.55 µm
Young Tae Byun, ∗ Young Min Jhon and Sun Ho Kim
Photonics Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Received 11 August 2004)
A single-mode GaAs/AlGaAs ridge waveguide phase modulator was fabricated using a MOCVD technique and a chemical wet etching method. The phase modulation of the P-p-n-N double het- erostructure waveguide phase modulator was measured as a function of the reverse bias voltages at a wavelength of 1.55 µm by using a Mach-Zehnder interference method. The measured switching voltage was 2.2 V, and a phase modulation efficiency as high as 40.9
◦/V ·mm for TE polariza- tion was achieved. This value corresponds to the highest experimental efficiency reported for both GaAs/AlGaAs and InGaAsP/InP phase modulator at the wavelength of 1.55 µm.
PACS numbers: 42
Keywords: P-p-n-N waveguide phase modulator, GaAs/AlGaAs ridge waveguide, Mach-Zehnder interferom- eter, Phase modulation efficiency
∗
