A low threshold buried heterostructure laser, a metal-semiconductor field effect transistor (MESFET), and a photodiode, have for the first time, been monolithically integrated on a semi-insulating GaAs substrate. This integrated optoelectronic circuit (IOEC) was operated as a rudimentary optical repeater. The incident optical signal is detected by the photodiode, amplified by the MESFET, and converted back to light by the laser. The gain bandwidth product of the repeater was measured to be 178 MHz

Bar-Chaim, N.

Lau, K. Y.

Ury, I.

Yariv, A.

English

Caltech Authors - Main

PROCEEDINGS OF SPIE
SPIEDigitalLibrary.org/conference-proceedings-of-spie
Gallium Aluminum Arsenide/Gallium
Arsenide Integrated Optical Repeater
Bar-Chaim, N, Lau, K, Ury, I, Yariv, A.
N Bar-Chaim, K Y Lau, I Ury, A. Yariv, "Gallium Aluminum Arsenide/Gallium
Arsenide Integrated Optical Repeater," Proc. SPIE 0466, Optical Interfaces for
Digital Circuits & Systems,  (10 May 1984); doi: 10.1117/12.941564
Event: 1984 Los Angeles Technical Symposium, 1984, Los Angeles, United
States
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 21 Feb 2020  Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
Gallium aluminum arsenide /gallium arsenide integrated optical repeater
N. Bar -Chaim, K.Y. Lau, I. Ury
Ortel Corporation
2015 W. Chestnut Street, Alhambra, California 91803
A. Yariv
California Institute of Technology, Pasadena, California 91125
Abstract
A low threshold buried heterostructure laser, a metal - semiconductor field effect
transistor (MESFET), and a photodiode, have for the first time, been monolithically
integrated on a semi -insulating GaAs substrate. This integrated optoelectronic circuit
(IOEC) was operated as a rudimentary optical repeater. The incident optial signal is
detected by the photodiode, amplified by the MESFET, and converted back to light by the
laser. The gain bandwidth product of the repeater was measured to be 178 MHz.
Introduction
The goal of integrated optoelectronics is to monolithically integrate optoelectronic
components with purely electronic components. In this paper we describe the demonstration
of the monolithic integration of a laser, a transistor, and a photodiode. The devices
were fabricated on a semi -insulating (SI) GaAs substrate. Use of a SI substrate allows
the devices to be electrically insulated from each other, and also reduces parasitics.
The simple circuit configuration used serves to illustrate the basic principles of
operation of IOECs in general, and sheds light on the expected performance characteristics
of more complicated repeater circuits.
Theory of operation
A schematic circuit of the IOEC is shown in Fig. 1. Light incident on the photodiode
causes a current to flow through the load resistor Rd. The change in current which flows
through the laser is the product of the transconductance (g ) of the MESFET and the change
in voltage which appears at the transistor gate. The DC opmtical gain of this repeater
is therefore,
G = npdnlgmRd
where n and n1 are the quantum efficiencies of the photodiode and laser (from one facet),
respectively. The -3 dB bandwidth of the repeater is
-
1 1
27 RdC
where C is the combined capacitance of the photodiode and MESFET. The gain- bandwidth
(GxB) product of the repeater is, therefore,
G x B = npdnlgm
2TrC
Device fabrication
A perspective view of the IOEC is shown in Fig. 2. The fabrication steps which were
used to realize the device are as follows. Epitaxial layers were grown on a semi -insulating
GaAs substrate by means of LPE in the following order: n -GaAs layer (n = 2 x 1016cm -3),
lower cladding layer ( n - Gao.65A1o.35As), active layer (undoped Gao.95Al0.05As), and an
upper cladding layer (p- Gao.65A1o.35As). The n -GaAs layer performs three functions: it
serves as the lower contact layer of the laser, the channel layer of the MESFET, and the
photosensitive /contact layer of the photodiode. After epitaxial growth, mesas were etched
down to the n -GaAs layer to form the laser waveguides. The width of the active layer thus
formed was = 2 um.
Subsequent to the mesa etch, a p- Gao.8Alo.2As and an undoped Gao.45Alo.55As layer were
regrown to embed the laser mesas. The p- Gao,3Al0,2As layer performs two functions: It
serves as the leakage- current blocking layer of the laser, and as the p -type window layer
of the photodiode. The undoped Gao.45Al0.55As layer was then selectively etched with HC1
SPIE Vol 466 Optical Interfaces for Digital Circuits and Systems (1984) / 65
enide/gallium arsenide rated 
 -Chaim, K.Y. Lau, . 
 
.  , 
  
9
buried heterostructure laser, a metal semiconductor  
r T),  ode, ,  
a semi-insul   
OEC) was operated s    
 e odiode, ET,  
 1
 
  
   
a semi-insulat ( )   
  
 
l ,  
ci
   
 lo res R,   
is the product of the transconductance    
g  ?ical gain  
 
n d ^ (fr  
 
B = -L_ _!_
 in-ban  
xB) product i th
G B = n n l
T
IOE is shown in Fig 2.  
fo  grown on a semi  
i following ord  -GaAs lay ( - 2 x 10 16 cnT 3 )  
  0 .Gs l 0 .3s  (und 0 .9s 0 .os  
laye (p- a 0 es l 0 . s  -GaAs layer performs   
  e  r,   
/contact r  wth,  
-GaAs layer to   
- 2 ym
Ga 0 .eAlo.zAs and an undoped Gao  «* s l 0  s   
 Ga 0 .eAl 0 .zAs layer performs   
cur ent blocking a the p-type w  
 0 . n s 0 .5
IE Vol. 466 tic l Interfaces for Digital Circuits and Systems (1984) /
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 21 Feb 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
everywhere except in the vicinity of the laser mesa. The exposed p- Gao.BAlo.2As layer was
then etched to define the photodiodes. Mesa etching down to the substrate was used to
isolate the devices from each other.
The entire wafer was next coated with Si02. Windows were etched in the Si02 to allow
contact to be made to the p -type layers of the laser and the photodiode. Zn diffusion was
performed to enhance the contact to the GaAlAs. Cr -Au was deposited and etched to form
contacts to the anodes of the laser and the photodiode. Contacts to the cathodes of the
laser, photodiode, and the MESFET source and drain, were formed by etching through the
Si02, lifting off AuGe /Au, and alloying. The MESFET gates were formed by etching a recess
into the n -GaAs MESFET channel until the desired thickness was obtained, and lifting off
Al. The MESFET thus formed had a gate length of 2 pm and a gate width of 250 Um. The
size of an individual die was 325 pm x 625 pm.
Device performance
The light vs current characteristic of the laser is shown in Figure 3. The threshold
current of 15 -20 mA is typical of this laser structure. The transconductance characteristics
of the FET are shown in Fig. 4, where the drain current is plotted against the voltage
across the series combination of the laser and the FET, at various gate voltages. One
interesting observation is that as the gate voltage is decreased from 0 to -8V, the drain
current decreases continuously, but with a slight further decrease in the gate voltage
(to -8.03V) the FET is completely cut -off and no current passes. The FET remains in the
cut -off state unless the gate voltage is raised above -7.7V, at which point the transistor
resumes its normal transconductance characteristic. It is believed that this bistability
is due to the coupling of the laser emission into the channel of the r'ia, which is
sensitive to optical radiation. An increase in the gate voltage increases the drain
current, and, hence, the amount of laser emission, which decreases the resistance of the
transistor channel and consequently further increases the drain current. This positive
feedback effect can lead to a bistable characteristic as that observed in our devices.
The operation of our IOEC as a repeater was demonstrated using the circuit arrangement
shown in Fig. 1. The load resistance Rd shown in Fig. 1 was a chip resistor mounted next
to the device. Laser emission from a separate GaAlAs laser diode is focused by a 20x
objective on the photodiode in the IOEC. The absolute DC responsivity of the photodiode
was measured separately to be 0.45 A /W. The absolute amount of light falling on the
detector can thus be determined by monitoring the DC photocurrent through Rd. The DC
optical gain G was measured to be 15 dB with Rd = 5.40, and 9.2 dB with Rd = 2.7 kO. This
is in good agreement with that expected by putting in the measured values of d (0.45 A /W),
Gm (6mmho) and n1 (0.4 W /A) into Eq. (1). The bandwidth of the repeater was measured
by modulating the source laser and observing on a RF spectrum analyzer the modulation in
the laser output from the IOEC with a separate PIN detector. The combined frequency
response of the external laser and detector was calibrated by repeating the measurement
with the IOEC removed and the optical output from the external laser was directly detected
by the external photodetector. The calibrated frequency responses of the repeater are
shown in Fig. 5. The -3 dB bandwidths are 29 MHz with Rd = 5.40 and 52 MHz with Rd = 2.7k0.
The high- frequency fall -off is at approximately 20 dB /dec, indicating that the response is
manifested by a simple RC combination. The observed bandwidth indicates a value of C in
the vicinity of 1 pF according to Eq. (2). This value is consistent with that obtained
by separate measurements2 and is within the range of values generally predicted for these
kind of devices. The measured gain- bandwidth product was 178 MHz.
Conclusion
The above results illustrate clearly the operational principle of an integrated opto-
electronic repeater circuit. The simple single- transistor circuit described above has a
GxB product of 178 MHz. It is obvious from Eq. (2), that GxB can be increased by improvement
in the performance of the individual components in the IOEC (increasing nod, nl, gm, and
decreasing C). However, it should be noted that the laser and detector if' our repeater
already display state -of- the -art performance. Nevertheless, an increase of a factor of
two in nlcan be obtained by reflection- coating the rear facet of the laser. The trans -
conductance of the FET can also be improved by reducing the gate - length to sub -micron
dimensions. With these improvements, the GxB product of our device would exceed 1 GHz.
This is the limit to the performance of a basic single- transistor repeater circuit.
Achieving higher gain- bandwidth products would require more complicated IOEC circuits
containing multiple stage transistor amplifiers.
Acknowledgement
This work was supported by the Defense Advanced Research Project Agency and the Naval
Research Laboratory.
66 / SPIE Vol 466 Optical Interfaces for Digital Circuits and Systems (1984)
of the laser mesa  p-Ga 0 e o m  
t   
f ea ot
ne coated with Si0 2 . S 2 t  
-type layers of the aser d  .  
con to the GaAlA  -Au was deposited and   
th laser and the photodiod   
r, de,   
2 , off AuGe/Au,   
-GaAs MESFET chan el until the desired thickness as ,  
 2 y a o 25 ym   
325 ym x 625 ym.
i 3   
-20 mA is typical f   
   
   
0  
y,  
o -8.03V) cut-off and o   
-of  state unles  the gate voltage is raised above 7.7V,   
character  s  
to the coupling of the laser em ssio  into the channel of the FET, whi  
  
nt, , ,   
  
k t  .
ci arr  
1. Rd shown in Fi      
 i f a 2  
in th IO   
separately to be 0.45 A   
.  
4fi  2 M.  
  np (0.45 A  
(6 r^ (0.4 W/A)   h of the repeater was measure  
i  
IO a separate PIN detector.  
 
f las w direct dete  
  
5  ^ 5 R =
frequency -of  is at ap roximately 0 /dec, indicating that  
co   
1 to Eq    
 f  
 gain-bandwidth 
i  
circ  gle-transistor a 
1  from Eq  ),   
(inc p , n i/ 9 /  
 n that the laser and detector in  
display state-of- -art  less,  
 ri^c by reflection-co the laser  trans  
FET can also be improved by reducing the gate- to sub-  
 e 1  
l t the performance of a basic single- sistor repeater circuit. 
bandwidth products would require more  
 
/ SPIE Vol. 466 Optical Interfaces for Digital Circuits and Syste s (
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 21 Feb 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
References
1. N. Bar -Chaim, I. Ury and A. Yariv, IEEE spectrum, 19, 38 (1982), and references
contained therein.
2. N. Bar- Chaim, K.Y. Lau, I. Ury and A. Yariv, Appl. Phys. Lett., 43, 261 (1983).
V2
Light Light
in I/ \I out
I I
Pin I I N-Laser
I IL ___ _I
Figure 1. Schematic diagram of the IOEC repeater. Also shown
are the bias networks for DC and RF testing of the circuit.
Si 02
n-GaAIAs
p-GaAIAs
n-GaAs
SI-GaAs
CrAu
Zn diffusion
P- GaAIAs
Active Region
n- GaAIAs
AuGe-Ni-Au
Cr-Au
Figure 2. A perspective view of the IOEC.
SPIE Vol 466 Optical Interfaces for Digital Circuits and Systems (1984) / 67
  -Chaim, I. Ury and A. Yariv, EEE ctrum, 9,  (   
t
  Chaim, K.Y. Lau, I. Ury and A. Yariv, Appl. ys. ,  (19
1  th IOEC repea   
CrAu ——— 
 di f i  
 
 i  
I
i0
 
Photodiode
2. t IO
I  Vol.  ti l Interfaces for Digital Circuits and Systems (1984) /
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 21 Feb 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
3IO 20
Id (mA)
Figure 3. Light vs. current
characteristics of the laser
in the IOEC.
30
â
E
0
25
/rv
-75 V
-
V9=-8V
10
5 Vg=-8.03V
15
1 2 3
V(DS+ Laser )
4 5
Figure 4. I -V characteristics of
the MESFET at various gate voltages.
Note the sudden total pinch -off at
Vg = -8.03V. The channel does not
recover until Vg is increased to
above -7.7V.
(dB) '
18
q12á
ä 8
5
29 MHz
1:20 dBAlecade
178MHz
58MHz
10 20 30 50 70 IOO
Frequency (MHz)
155MHz
200 300
Figure 5. Frequency response of the
repeater unit at two values of the bias
resistor Rd. Top curve: Rd = 5.452,
lower curve: Rd = 2. 7kS2.
68 / SPIE Vol 466 Optical Interfaces for Digital Circuits and Systems (1984)
20
< 
Q 
45 
(  + Laser
3  .  
 
4  -V characteri  
ga vol  
total pinch-  
  
 
     100  
5   
 
^   ^ = 5.4S7  
  = 2. fi
 / SPIE Vol. 4 6 Optical Interfaces for Digital Circuits and Syste  
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 21 Feb 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use


Gallium Aluminum Arsenide/Gallium Arsenide Integrated Optical Repeater

PROCEEDINGS OF SPIE
SPIEDigitalLibrary.org/conference-proceedings-of-spie
Gallium Aluminum Arsenide/Gallium
Arsenide Integrated Optical Repeater
Bar-Chaim, N, Lau, K, Ury, I, Yariv, A.
N Bar-Chaim, K Y Lau, I Ury, A. Yariv, "Gallium Aluminum Arsenide/Gallium
Arsenide Integrated Optical Repeater," Proc. SPIE 0466, Optical Interfaces for
Digital Circuits & Systems,  (10 May 1984); doi: 10.1117/12.941564
Event: 1984 Los Angeles Technical Symposium, 1984, Los Angeles, United
States
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 21 Feb 2020  Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
Gallium aluminum arsenide /gallium arsenide integrated optical repeater
N. Bar -Chaim, K.Y. Lau, I. Ury
Ortel Corporation
2015 W. Chestnut Street, Alhambra, California 91803
A. Yariv
California Institute of Technology, Pasadena, California 91125
Abstract
A low threshold buried heterostructure laser, a metal - semiconductor field effect
transistor (MESFET), and a photodiode, have for the first time, been monolithically
integrated on a semi -insulating GaAs substrate. This integrated optoelectronic circuit
(IOEC) was operated as a rudimentary optical repeater. The incident optial signal is
detected by the photodiode, amplified by the MESFET, and converted back to light by the
laser. The gain bandwidth product of the repeater was measured to be 178 MHz.
Introduction
The goal of integrated optoelectronics is to monolithically integrate optoelectronic
components with purely electronic components. In this paper we describe the demonstration
of the monolithic integration of a laser, a transistor, and a photodiode. The devices
were fabricated on a semi -insulating (SI) GaAs substrate. Use of a SI substrate allows
the devices to be electrically insulated from each other, and also reduces parasitics.
The simple circuit configuration used serves to illustrate the basic principles of
operation of IOECs in general, and sheds light on the expected performance characteristics
of more complicated repeater circuits.
Theory of operation
A schematic circuit of the IOEC is shown in Fig. 1. Light incident on the photodiode
causes a current to flow through the load resistor Rd. The change in current which flows
through the laser is the product of the transconductance (g ) of the MESFET and the change
in voltage which appears at the transistor gate. The DC opmtical gain of this repeater
is therefore,
G = npdnlgmRd
where n and n1 are the quantum efficiencies of the photodiode and laser (from one facet),
respectively. The -3 dB bandwidth of the repeater is
- 1 1
27 RdC
where C is the combined capacitance of the photodiode and MESFET. The gain- bandwidth
(GxB) product of the repeater is, therefore,
G x B = npdnlgm
2TrC
Device fabrication
A perspective view of the IOEC is shown in Fig. 2. The fabrication steps which were
used to realize the device are as follows. Epitaxial layers were grown on a semi -insulating
GaAs substrate by means of LPE in the following order: n -GaAs layer (n = 2 x 1016cm -3),
lower cladding layer ( n - Gao.65A1o.35As), active layer (undoped Gao.95Al0.05As), and an
upper cladding layer (p- Gao.65A1o.35As). The n -GaAs layer performs three functions: it
serves as the lower contact layer of the laser, the channel layer of the MESFET, and the
photosensitive /contact layer of the photodiode. After epitaxial growth, mesas were etched
down to the n -GaAs layer to form the laser waveguides. The width of the active layer thus
formed was = 2 um.
Subsequent to the mesa etch, a p- Gao.8Alo.2As and an undoped Gao.45Alo.55As layer were
regrown to embed the laser mesas. The p- Gao,3Al0,2As layer performs two functions: It
serves as the leakage- current blocking layer of the laser, and as the p -type window layer
of the photodiode. The undoped Gao.45Al0.55As layer was then selectively etched with HC1
SPIE Vol 466 Optical Interfaces for Digital Circuits and Systems (1984) / 65
enide/gallium arsenide rated 
 -Chaim, K.Y. Lau, . 
 
.  , 
  
9
buried heterostructure laser, a metal semiconductor  
r T),  ode, ,  
a semi-insul   
OEC) was operated s    
 e odiode, ET,  
 1
 
  
   
a semi-insulat ( )   
  
 
l ,  
ci
   
 lo res R,   
is the product of the transconductance    
g  ?ical gain  
 
n d ^ (fr  
 
B = -L_ _!_
 in-ban  
xB) product i th
G B = n n l
T
IOE is shown in Fig 2.  
fo  grown on a semi  
i following ord  -GaAs lay ( - 2 x 10 16 cnT 3 )  
  0 .Gs l 0 .3s  (und 0 .9s 0 .os  
laye (p- a 0 es l 0 . s  -GaAs layer performs   
  e  r,   
/contact r  wth,  
-GaAs layer to   
- 2 ym
Ga 0 .eAlo.zAs and an undoped Gao  «* s l 0  s   
 Ga 0 .eAl 0 .zAs layer performs   
cur ent blocking a the p-type w  
 0 . n s 0 .5
IE Vol. 466 tic l Interfaces for Digital Circuits and Systems (1984) /
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 21 Feb 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
everywhere except in the vicinity of the laser mesa. The exposed p- Gao.BAlo.2As layer was
then etched to define the photodiodes. Mesa etching down to the substrate was used to
isolate the devices from each other.
The entire wafer was next coated with Si02. Windows were etched in the Si02 to allow
contact to be made to the p -type layers of the laser and the photodiode. Zn diffusion was
performed to enhance the contact to the GaAlAs. Cr -Au was deposited and etched to form
contacts to the anodes of the laser and the photodiode. Contacts to the cathodes of the
laser, photodiode, and the MESFET source and drain, were formed by etching through the
Si02, lifting off AuGe /Au, and alloying. The MESFET gates were formed by etching a recess
into the n -GaAs MESFET channel until the desired thickness was obtained, and lifting off
Al. The MESFET thus formed had a gate length of 2 pm and a gate width of 250 Um. The
size of an individual die was 325 pm x 625 pm.
Device performance
The light vs current characteristic of the laser is shown in Figure 3. The threshold
current of 15 -20 mA is typical of this laser structure. The transconductance characteristics
of the FET are shown in Fig. 4, where the drain current is plotted against the voltage
across the series combination of the laser and the FET, at various gate voltages. One
interesting observation is that as the gate voltage is decreased from 0 to -8V, the drain
current decreases continuously, but with a slight further decrease in the gate voltage
(to -8.03V) the FET is completely cut -off and no current passes. The FET remains in the
cut -off state unless the gate voltage is raised above -7.7V, at which point the transistor
resumes its normal transconductance characteristic. It is believed that this bistability
is due to the coupling of the laser emission into the channel of the r'ia, which is
sensitive to optical radiation. An increase in the gate voltage increases the drain
current, and, hence, the amount of laser emission, which decreases the resistance of the
transistor channel and consequently further increases the drain current. This positive
feedback effect can lead to a bistable characteristic as that observed in our devices.
The operation of our IOEC as a repeater was demonstrated using the circuit arrangement
shown in Fig. 1. The load resistance Rd shown in Fig. 1 was a chip resistor mounted next
to the device. Laser emission from a separate GaAlAs laser diode is focused by a 20x
objective on the photodiode in the IOEC. The absolute DC responsivity of the photodiode
was measured separately to be 0.45 A /W. The absolute amount of light falling on the
detector can thus be determined by monitoring the DC photocurrent through Rd. The DC
optical gain G was measured to be 15 dB with Rd = 5.40, and 9.2 dB with Rd = 2.7 kO. This
is in good agreement with that expected by putting in the measured values of d (0.45 A /W),
Gm (6mmho) and n1 (0.4 W /A) into Eq. (1). The bandwidth of the repeater was measured
by modulating the source laser and observing on a RF spectrum analyzer the modulation in
the laser output from the IOEC with a separate PIN detector. The combined frequency
response of the external laser and detector was calibrated by repeating the measurement
with the IOEC removed and the optical output from the external laser was directly detected
by the external photodetector. The calibrated frequency responses of the repeater are
shown in Fig. 5. The -3 dB bandwidths are 29 MHz with Rd = 5.40 and 52 MHz with Rd = 2.7k0.
The high- frequency fall -off is at approximately 20 dB /dec, indicating that the response is
manifested by a simple RC combination. The observed bandwidth indicates a value of C in
the vicinity of 1 pF according to Eq. (2). This value is consistent with that obtained
by separate measurements2 and is within the range of values generally predicted for these
kind of devices. The measured gain- bandwidth product was 178 MHz.
Conclusion
The above results illustrate clearly the operational principle of an integrated opto-
electronic repeater circuit. The simple single- transistor circuit described above has a
GxB product of 178 MHz. It is obvious from Eq. (2), that GxB can be increased by improvement
in the performance of the individual components in the IOEC (increasing nod, nl, gm, and
decreasing C). However, it should be noted that the laser and detector if' our repeater
already display state -of- the -art performance. Nevertheless, an increase of a factor of
two in nlcan be obtained by reflection- coating the rear facet of the laser. The trans -
conductance of the FET can also be improved by reducing the gate - length to sub -micron
dimensions. With these improvements, the GxB product of our device would exceed 1 GHz.
This is the limit to the performance of a basic single- transistor repeater circuit.
Achieving higher gain- bandwidth products would require more complicated IOEC circuits
containing multiple stage transistor amplifiers.
Acknowledgement
This work was supported by the Defense Advanced Research Project Agency and the Naval
Research Laboratory.
66 / SPIE Vol 466 Optical Interfaces for Digital Circuits and Systems (1984)
of the laser mesa  p-Ga 0 e o m  
t   
f ea ot
ne coated with Si0 2 . S 2 t  
-type layers of the aser d  .  
con to the GaAlA  -Au was deposited and   
th laser and the photodiod   
r, de,   
2 , off AuGe/Au,   
-GaAs MESFET chan el until the desired thickness as ,  
 2 y a o 25 ym   
325 ym x 625 ym.
i 3   
-20 mA is typical f   
   
   
0  
y,  
o -8.03V) cut-off and o   
-of  state unles  the gate voltage is raised above 7.7V,   
character  s  
to the coupling of the laser em ssio  into the channel of the FET, whi  
  
nt, , ,   
  
k t  .
ci arr  
1. Rd shown in Fi      
 i f a 2  
in th IO   
separately to be 0.45 A   
.  
4fi  2 M.  
  np (0.45 A  
(6 r^ (0.4 W/A)   h of the repeater was measure  
i  
IO a separate PIN detector.  
 
f las w direct dete  
  
5  ^ 5 R =
frequency -of  is at ap roximately 0 /dec, indicating that  
co   
1 to Eq    
 f  
 gain-bandwidth 
i  
circ  gle-transistor a 
1  from Eq  ),   
(inc p , n i/ 9 /  
 n that the laser and detector in  
display state-of- -art  less,  
 ri^c by reflection-co the laser  trans  
FET can also be improved by reducing the gate- to sub-  
 e 1  
l t the performance of a basic single- sistor repeater circuit. 
bandwidth products would require more  
 
/ SPIE Vol. 466 Optical Interfaces for Digital Circuits and Syste s (
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 21 Feb 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
References
1. N. Bar -Chaim, I. Ury and A. Yariv, IEEE spectrum, 19, 38 (1982), and references
contained therein.
2. N. Bar- Chaim, K.Y. Lau, I. Ury and A. Yariv, Appl. Phys. Lett., 43, 261 (1983).
V2
Light Light
in I/ \I out
I I
Pin I I N-Laser
I IL ___ _I
Figure 1. Schematic diagram of the IOEC repeater. Also shown
are the bias networks for DC and RF testing of the circuit.
Si 02
n-GaAIAs
p-GaAIAs
n-GaAs
SI-GaAs
CrAu
Zn diffusion
P- GaAIAs
Active Region
n- GaAIAs
AuGe-Ni-Au
Cr-Au
Figure 2. A perspective view of the IOEC.
SPIE Vol 466 Optical Interfaces for Digital Circuits and Systems (1984) / 67
  -Chaim, I. Ury and A. Yariv, EEE ctrum, 9,  (   
t
  Chaim, K.Y. Lau, I. Ury and A. Yariv, Appl. ys. ,  (19
1  th IOEC repea   
CrAu ——— 
 di f i  
 
 i  
I
i0
 
Photodiode
2. t IO
I  Vol.  ti l Interfaces for Digital Circuits and Systems (1984) /
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 21 Feb 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
3
IO 20
Id (mA)
Figure 3. Light vs. current
characteristics of the laser
in the IOEC.
30
â
E
0
25
/rv
-75 V
-
V9=-8V
10
5 Vg=-8.03V
15
1 2 3
V(DS+ Laser )
4 5
Figure 4. I -V characteristics of
the MESFET at various gate voltages.
Note the sudden total pinch -off at
Vg = -8.03V. The channel does not
recover until Vg is increased to
above -7.7V.
(dB) '
18
q12
á
ä 8
5
29 MHz
1:20 dBAlecade
178MHz
58MHz
10 20 30 50 70 IOO
Frequency (MHz)
155MHz
200 300
Figure 5. Frequency response of the
repeater unit at two values of the bias
resistor Rd. Top curve: Rd = 5.452,
lower curve: Rd = 2. 7kS2.
68 / SPIE Vol 466 Optical Interfaces for Digital Circuits and Systems (1984)
20
< 
Q 
45 
(  + Laser
3  .  
 
4  -V characteri  
ga vol  
total pinch-  
  
 
     100  
5   
 
^   ^ = 5.4S7  
  = 2. fi
 / SPIE Vol. 4 6 Optical Interfaces for Digital Circuits and Syste  
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 21 Feb 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use


https://authors.library.caltech.edu/101881/1/65.pdf

Gallium Aluminum Arsenide/Gallium Arsenide Integrated Optical Repeater

Abstract

Similar works

Full text

Available Versions

Caltech Authors - Main

Caltech Authors - Main