Integrated optoelectronic substrate

An integrated optoelectronic substrate is provided. A molded optical substrate having a surface, a core region having a first optical surface, and a cladding region is formed with the core region being at least partially surrounded by the cladding region. An interconnect board having a first surface and a second surface is disposed on the molded optical substrate, thereby operably coupling the molded optical substrate to the interconnect board.

FIELD OF THE INVENTION 
This invention relates, in general, to optics and, in particular, to 
integration of optoelectronic elements. 
BACKGROUND OF THE DISCLOSURE 
At present, interconnection between optical components and standard 
electronic components is a difficult task which is expensive. Generally, 
the interconnection or integration of optical components and standard 
electrical components is achieved manually or semiautomatically, thereby 
making the integration complex, inefficient, and not suitable for high 
volume manufacturing. Since the integration of optical components and 
electrical components is not suitable for high volume manufacturing, 
manufacture of systems and products that would utilize advantages of both 
optics and electronics synergistically are generally not manufactured. 
Conventionally, interconnection between optical components and standard 
electronics is achieved by carefully aligning a working portion of a 
photonic device to an optically conductive means and subsequently affixing 
the working portion of the photonic device to the conductive means, 
thereby optically coupling the conductive means to the photonic device. 
The photonic device is then electrically coupled to standard electrical 
components; however, as with the coupling of the working portion of the 
photonic device to the conducting means, the electrical coupling is 
achieved manually, thereby providing several problems, such as being 
extremely labor intensive, costly, inaccuracy of alignment. Thus, 
conventional interconnection methods and structures for optical and 
standard electronic components are not suitable for high volume 
manufacturing. Further, since conventional methods and structures are not 
suitable for high volume manufacturing, products capable of using the 
advantages of both optical components and electrical components are not 
manufactured. Thus, products utilizing the synergistic advantages of both 
optics and electronics are not realized. 
At present, with the difficulty of integrating optical and electronic 
components, integration of optical and electronic components that are at a 
substrate or board level is also a difficult task. 
It can be readily seen that conventional methods and structures for 
integrating photonic and electrical components have severe limitations 
which prevents realization of advantages of both photonic and electrical 
components. Also it is evident that the conventional methods and 
structures are not only complex and expensive, but also not effective for 
high volume manufacturing. Therefore, a method and structure for 
facilitating the integration of photonic devices and standard electrical 
components, as well as integration at a board or substrate level would be 
highly desirable.

DETAILED DESCRIPTION OF THE DRAWINGS 
In the FIGURE, an enlarged simplified perspective view of an integrated 
optoelectronic module 101 is shown. Integrated optoelectronic module 101 
having several components, such as a molded optical substrate 104, a 
photonic device 124, an optical connector 130, and an interconnect board 
or an interconnect substrate 140 is illustrated. It should be understood 
that integrated optoelectronic module 101 shown in the FIGURE is greatly 
simplified so as to more clearly illustrate the present invention. 
Molded optical substrate 104 includes a surface 105, a plurality of 
electrical members 106, e.g., electrical members 107 and 108, a plurality 
of core regions 109, a cladding region 110, ends 111 and 112, surface 113, 
conductive portions 116 and 117, and optical port 119 is shown. Photonic 
device 124 is shown to include a working portion 125 that is exploded away 
from molded optical substrate 104. Optical connector 130 is shown to 
include a optical cable 131, a body 133 having a surface 134, optical 
surfaces 135, and an alignment guide 137, e.g., alignment pins 136. 
Interconnect board 140 is shown to include surfaces 141, 142, and 143, 
bonding pads 146, 147, 149, and 150, electrical traces 155, 156, 157, 158, 
and 159, a conductive member 163, electrical contacts 148, e.g., 
electrical contact 151, and electrical cable 165. 
In the present invention, molded optical substrate 104 is made by any 
suitable molding method or technique, such as injection molding, transfer 
molding, or the like. Additionally, any suitable material or materials, 
such as a plastic material, an epoxy material, a polyimide material, or 
the like are used. Molding of the molded optical substrate 104 provides 
the plurality of core regions 109 surrounded by cladding region 110. 
Typically, the plurality of core regions 109 and cladding region 110 are 
made of a hard optically transparent polymer, with the plurality of core 
regions 109 having a higher refractive index than does cladding region 
110, thus allowing for efficient light guiding and transmission through 
the plurality of core regions 109. For example, with the plurality of core 
regions 109 and cladding region 110 being made of a molding material 
having a refractive index ranging from 1.3 to 1.7, the refractive index of 
the plurality of core regions 109 is 0.01 higher than cladding region 110, 
thereby enabling efficient guiding of light or optical signals through the 
plurality of core regions 109. 
Further, molded optical substrate 104 is molded to any suitable size and 
shape; however, so as to better integrated molded optical substrate 104 
with interconnect substrate 140, both molded optical substrate 104 and 
interconnect substrate 140 are similar in size and shape, thereby 
facilitating coupling of the plurality of conductive members 106 with the 
plurality of electrical contacts 148. 
Also, molded optical substrate 104 is formed so that ends 111 and 112 
expose optical surfaces 110 or portions of the plurality of core regions 
109, thereby enabling the exposed portion or optical surfaces 110 of the 
plurality of core regions 109 to be optically coupled with other optical 
structures. In addition, it should be understood that the plurality of 
core region 109 can be formed into a variety of different configurations, 
such as being curved, having an end with a reflective surface, splitting, 
e.g., bifurcated, or the like in molded optical substrate 104. Thus, the 
plurality of core regions 109 can perform a variety of optical functions. 
As illustrated in the FIGURE, optical surfaces 110 of the plurality core 
regions are exposed on surface 113 of end 111, thereby enabling optical 
coupling of the plurality of core regions 109 with working portion 125 of 
photonic device 124. Additionally, it should be understood that end 112 
also has a surface that exposes optical surfaces of the plurality of core 
regions 109 that enables optical coupling of optical surfaces 135 of 
optical connector 130 with the plurality of core regions 109. 
Optical port 119 illustrates an optical communication port that optically 
couples molded optical substrate 104 to interconnect board 140. More 
specifically, optical port 119 is made by molding a reflective surface in 
molded optical substrate 104, thereby reflecting light or optical signals 
either to or from molded optical substrate 104 or interconnect board 140, 
respectively. The reflective surface is made by any suitable method, such 
as providing a metal reflective surface, providing a change in refractive 
index, or the like. Generally, the reflective surface is positioned at an 
angle ranging from 20 to 80 degrees, with a preferred angle of 45 degrees. 
For example, with optical signals traveling in one of the plurality of 
core regions 109 and striking the reflective surface, the optical signals 
are reflected through optical port and into photonic device 164. In yet 
another example, with the optical signals being generated from photonic 
device 164, the optical signals pass through interconnect substrate 140 
and through optical port 119. The optical signals are then reflected off 
of the reflective surface and into one of the core regions of the 
plurality of core regions 109. 
Thus, optical signals can enter and leave molded optical substrate by a 
variety of paths, thereby enhancing flexibility and speed of integrated 
optoelectronic module 101. 
The plurality of electrical members is made of any suitable electrically 
conductive material, such as copper, aluminum, metal alloys, and the like. 
However, in a preferred embodiment of the present invention, the plurality 
of electrical members is made of lead frame members that are embedded in 
molded optical substrate during the molding process of molded optic 
substrate. Upon completion of the molding process, the lead frame members 
are trimmed and formed to make the plurality of electrical members 106, 
thereby providing electrical coupling between molded optical substrate 104 
and interconnect substrate 140. More specifically, the plurality of 
electrical members 106 engage electrical contacts 148, thereby 
electrically coupling molded optical substrate 104 and interconnect 
substrate 140. Further, the lead frame members embedded in molded optical 
substrate extend from the plurality of electrical members 106 to surface 
113 forming conductive portions 116 and 117. Generally, conductive portion 
116 is a ground strap with conductive portions 117 being individually 
identified with one of the plurality of electrical members 106, thereby 
enabling electrical signals to pass through the lead frame members. 
Photonic device 124 is made of any suitable optoelectronic device, such as 
a phototransmitter, a photoreceiver, or a bifunctional photonic device, 
i.e., an optoelectronic device that is both a phototransmitter and a 
photoreceiver. When the optoelectronic device is a phototransmitter, the 
optoelectronic device is any suitable phototransmitting device, such as a 
laser, e.g., vertical cavity surface emitting layer (VCSEL), a light 
emitting diode (LED), or the like. Alternatively, when optoelectronic 
device 124 is an photoreceiver, the optoelectronic device is any suitable 
photoreceiving device, such as a photodetector, a photodiode, e.g., p-i-n 
photodiode, or the like. In addition, depending upon a specific 
application, photonic device 124 is configured either as an array having 
photoreceiver, phototransmitter, a combination of both photoreceivers and 
phototransmitters. 
Generally, photonic device 124 is assembled to molded optical substrate 104 
by any suitable well-known method in the art, such as manually, 
semiautomatically, or automatically. However, in a preferred embodiment of 
the present invention, assembly of photonic device 124 to molded optical 
substrate 104 is achieved by an automated system, such as a robot arm or 
the like. 
Optical connector 130 is made with optical cable 131 incorporated into body 
133. By incorporating optical cable 131 into body 133, individual optical 
fibers in optical cable 131 are positionally fixed in relation to 
alignment pins 136, thereby providing optical surfaces 135 of the 
individual optical fibers on surface 134. 
Alignment guide 137 is made in any suitable configuration, such as 
alignment pins 136, alignment keys and ways, and the like. By way of 
example, with alignment guide 137 being alignment pins 136 and with 
alignment pins 136 have reciprocal openings in end 112 of molded optical 
substrate, insertion of alignment pins 136 into the reciprocal openings 
aligns optical surfaces 135 to the plurality of core regions 109 at end 
112 of molded optical substrate 104. Thus, allowing a light signal to be 
transferred from molded optical substrate 104 to optical connector 130 in 
either direction. In a preferred embodiment of the present invention, 
optical connector 130 is detachably engaged with end 112 of molded optical 
substrate 104, thereby bringing optical surfaces 135 and the plurality of 
core regions 109 together so as to operably connect the plurality of core 
regions 109 and optical surfaces 135. 
Interconnect substrate 140 is made of any suitable interconnect substrate, 
such as a printed circuit board (PCB), an FR4 board, silicon interconnect 
substrate, a ceramic interconnection substrate, or the like. Typically 
interconnection substrate 140 provides a plurality of electrical traces, 
represented by electrical traces 155-159, on interconnect substrate 140. 
Electrical traces 155-159 electrically couple a variety of components, 
such as conductive member 163, photonic device 164, electric cable 165, 
integrated circuit 166. It should be understood that the variety of 
components varies in specific applications, thus discrete devices, such as 
capacitors, transistors, resistors, and the like can also be electrically 
coupled through electrical traces 155-159. Additionally, interconnect 
substrate 140 can electrically communicate though conductive member 163 or 
electrical cable 165. Thus, interconnect substrate 140 is integratable 
with other electronic devices and systems, such as boards, computers, and 
the like. 
Interconnection between molded optical substrate 104 and interconnection 
substrate 140 is accomplished either optically through optical port 119 to 
photonic device 164 or electrically through the plurality of electrical 
members 106 to electrical contacts 148, thereby integrating molded optical 
substrate 104 and interconnection substrate 140. By integrating optical 
substrate 104 and interconnection substrate 140, advantages of both optics 
and electronics are utilized. For example, since molded optical substrate 
104 and interconnect substrate 140 molded optical substrate 104 transports 
more information at greater speeds than an electronic system alone. 
Generally, interconnect substrate 140 is positioned on molded optical 
substrate 104 and aligned by any suitable method, such as machine vision, 
physical alignment, e.g., tabs 167, or the like. 
Further, attachment of interconnect substrate 140 to molded optical 
substrate 104 is either permanent or detachably engaged depending on the 
specific application. In the case of the permanent attachment, molded 
optical substrate is affixed to interconnect substrate with any suitable 
optical adhesive, such as an epoxy, a polyimide, a plastic, or the like. 
If optical port 119 is used, then selection of the optical adhesive is 
dependent upon both adhesive qualities and the refractive index if optical 
port 119 is to be used. Generally, the refractive index of the optical 
adhesive ranges from 1.3 to 1.7; however, by selecting a refractive index 
that is similar to the plurality of core regions 109 allows for an optimal 
transference of light from optical port 119 to photonic device 164. 
While we have shown and described specific embodiments of the present 
invention, further modifications and improvements will occur to those 
skilled in the art. We desire it to be understood, therefore, that this 
invention is not limited to the particular forms shown and we intend in 
the appended claims to cover all modifications that do not depart from the 
spirit and scope of this invention.