The interconnection required to boosting the performance of Internet switches is directly proportional to the final outcome of data aggregation. As the next-generation Internet switches emerge, we need a reliable interconnection to make them work. That is what you will get by using optical PCB.
In this article, we define what an optical circuit board is, the relevance in the market and some of the benefits.
What is an Optical Printed Circuit Board?
It is a type of circuit board used to produce dedicated interconnects, required for the connection of optical interconnects.
Optical Interconnects on a PCB?
You may be wondering why these interconnections are brought to the PCB-level. Given the ever-increasing use cases and or applications of Printed Circuit Boards (PCBs), it is not entirely surprising that optical interconnections are made here.
At the core is the need to leverage fiber optics, as a means to an “end” – towards forging an integration of optical interconnects onto Printed Circuit Boards (PCBs).
This is a step away from the conventional use of chip-to-chip interconnects, which, though have been in use for some decades, is now giving way to newer technologies.
Today, we can now commercialize optical interconnects, on the basis of Photonic Integrated Circuits (PICs).
Although today’s optical PCB is still based on a construction out of COTS components, we are optimistic of what the future holds.
Market Opportunity: Why Optical PCBs Became Popular
The primary goal for producing optical circuits is to streamline the speed of processing data rates.
Other reasons include:
1. The Need to Prevent Signal Loss Issues
The current Internet switches are not fully-equipped to handle the data rates. With the expectations of higher data rates from the next-generation Internet switches and high-end computers, it has become imperative to step-up on the performance of these switches.
However, the current switches are processing data packets (rates) in Gigabytes per second (Gbit/s). This is lower than the anticipated Terabytes per second (Tbit/s) data rates of next-generation Internet switches.
If the current switches and interconnection technologies are relied for this, one can be sure of signal loss, in the process of transmitting data rates.
2. The Wire Geometry Consideration
This is another important consideration. The geometry of the wire makes it nearly impossible to leverage the existing electrical interconnection technology. For example, we currently have more of copper wiring that inhibits data transmission rates in the following ways:
- The inverse proportion of the wire’s length to the cross-sectional area, and the proportion of the resistance to the wire’s length.
- The wire is usually thinner, and this further reduces the data transmission rates.
3. Limitations in Scaling
There is currently a challenge in scaling or extending the performances of electrical/optical interconnects. This is because of several factors, such as:
- Reflection
- Signal loss
- Crosstalk
- Space constraints that don’t allow for thicker wire usage
- An increase in noise and power consumption, due to the use of a harder connection to reduce conversion time.
- An increase in power consumption and operational costs for scaling current interconnects, up to 100 Gb/s.
How Optical Interconnects are Integrated into PCBs
Optical interconnects are currently constructed from the COTS components, but there are indications that, in the future, we will have these interconnects directly printed on the circuits’ substrates.
It is also worth noting that the integration of optical waveguides in the PCBs also aid the integration of optical interconnects. With the potentials, these would greatly improve the overall performances of the onboard interconnects.
The Advantages of Optical PCB
Besides reducing the link length for the high-speed electrical signals, the integration of optical interconnects into PCBs also offer these benefits:
a. Independent Propagation of Signals
Signal loss and integrity problems are the common challenges with conventional electrical interconnection technology. This is now been tackled with the fusion of optical interconnects into PCBs.
The optical signals can now make independent propagations, devoid of the restrictions in space. This is also enhanced by the use of an imaging processing technology that delivers good dimensional integrity of the waveguide layer.
b. Improved Speed and Overall Performance
The overall performance of the optical circuit board is assured, because of these reasons:
- The optical interconnection’s speed is separated from the interconnection channel.
- A photo-imaginable waveguide material is used to help meet the processing and functional requirements.
c. Improved Reliability
With the optical PCB technology, one can be certain of deriving improved reliability of the signals, courtesy of these reasons:
- Optical signals can propagate in three-dimensional (3D) free space.
- There is a considerable increase in the data transmission rate.
d. Balancing Performance and Cost
It is now possible to have both an improved performance at affordable costs, with the new optical PCB framework.
In addition to reducing the physical size of the electrical connection, it also aids the reduction of power consumed, while cutting down on the cost of the material used.
Typical Applications for Optical PCB
With the inputs of the optical circuit boards, we can now see that the use cases for these boards are further expanding. Now, you can use these boards to enhance the different applications and communications.
The following are some examples of the typical applications:
- Opto-micromachine
- Telecommunications and;
- Photonic interconnection
Besides the above, optical circuit boards have also been used in other places. Most importantly, the photonics and optical interconnects jointly enable the usage in advanced applications, such as:
- Future Telecommunication Networks: these are used to reduce the numbers of electronic components in both base stations and edge servers used for future telecommunication networks, such as 5G.
- Quantum Computing: photonics is used here to ease cryogenic requirements, as well as serving as an alternative to superconductors commonly used in quantum computing.
- AI Applications: the applications and or devices powered by or leveraging Artificial Intelligence (AI) also benefit from optical circuit boards. In this case, both Integrated Circuits (ICs) and optical interconnects are used to facilitate a higher and speedier data transfer between the systems and different components in a datacenter.
Design Constraints for Optical PCBs
Although we are adopting optical circuit boards into modern consumer electronics and related products, there are still some gaps that need to be filled.
Here are some of the constraints or challenges facing the massive adoption of optical PCBs:
a. Immature Technology
The first challenge is the inability to further the advancement of the technology required for building the optical circuit boards.
In the past, heavy reliance was placed on the use of material and processing technology for the fabrication of waveguides. With the recent developments, more efforts need to be in place for “mature manufacturing technology” to be used, especially for the production of optical circuit boards in their numbers (mass productions).
b. The Material’s Platform Needs to be Considered
One important consideration is the choice of the material platform to be used. As a rule of thumb, the platform needs to be scalable, as well as enabling the fabrication of interconnects, in-between the photonic circuits.
c. The Choice of I/O Interfaces
The Inputs and Outputs (I/Os) interfaces are also worth considering. In this case, we are looking at the intersection or interface where the chip meets the circuit board.
d. Reliability of the Final Product
There is a need to be certain of the reliability of the final product. This is important, considering that the waveguide layer, after being fabricated, would need to be laminated to a conventional electrical layer.
Therefore, the adhesion or reliability of the final product is a major concern, seeing that the material configuration of the two layers differ.
Thus, it is important to have a balanced view and process to the method, considering that the waveguide material would be subject to degradation, provided the lamination is higher.
e. The Need to have a Functional Photo-Imaginable Material
There is also a need to have the photo-imaginable material developed to match both the processing and functional requirements. This is because the material is used to make-up the cladding layer and waveguide core.
Here are the different requirements:
- The cladding layer should be compatible with traditional circuit board materials. An example is Flame Retardant 4 (FR-4). By so doing, the cladding material will provide excellent adhesion between the electrical and optical layers.
- On the other hand, the waveguide core material should meet the basic functional requirements, such as optical loss. The core materials should also match the processing requirement, an example being viscosity.
f. Good Dimensional Integrity
As a must, the waveguide core layer must be in a good dimensional integrity, especially after the development. A coating method that provides excellent thickness distribution across the circuit board is commonly used for this purpose.
Conclusion
In conclusion, you can use optical circuit boards can be used as a means to further the transfer of data across different electronic components and devices. In addition, you can further niche-down the use of these circuit boards, as per the applications.
For example, there is the fiber optic circuit board used to conduct or transfer large amounts of data at faster speeds, and with additional safeguards.
On the other hand, there is the oscilloscope PCB, which is a device dedicated to measuring different parameters of electric signals. By this provision, the device for these purposes:
- Monitoring the operation of the electronic equipment.
- Checking the circuit board and its components’ quality.
Therefore, contact a professional optical PCB manufacturer today to help integrate the optical interconnects into your circuit boards for optimum data and signal transfer rates.
