Optical fiber array units (FAU) are essential devices for high-precision connection of optical waveguide elements and optical fibers in coherent optical fiber systems, co-packaged optics and other fiber systems and platforms. Coherent optical communication systems use phase information of light to achieve high-speed and large-capacity data transmission. Therefore, it is important to minimize connection loss and return loss to maintain light signal transmission efficiency and signal quality. To fulfill this role, fiber arrays require extremely high precision and stability in the connection of optical waveguide elements (silicon photonics, PLC: optical waveguide circuits, self-forming waveguide, etc.) and optical fibers.
V-groove substrates and ultra-precision processing technology
Optical fiber arrays are manufactured by precisely arranging and fixing optical fibers in a horizontal row on V-groove substrates, which are mainly made of glass or silicon and formed by etching or grinding using semiconductor processing technology. The V-groove formation accuracy is controlled at the nanometer (nm) level, requiring positioning accuracy on the order of sub-microns (0.1 µm) relative to the outer diameter of the optical fiber (typically 125µm).
This high-precision positioning ensures that the optical fiber core is precisely aligned to maximize the coupling efficiency of the optical signal to the optical waveguide element. In addition, fiber end faces are polished with physical contact (PC) and angle polish (APC) to reduce return loss and insertion loss. In particular, APC minimizes signal degradation due to reflection by allowing light reflections to escape at an angle of about 8 degrees.
Technologies for Reducing Connection Loss
Connection loss in optical fiber arrays can be divided into insertion loss and return loss.
Insertion loss is caused by fiber core misalignment and end-face quality variations.
Return loss is caused by interference and returned light from reflected light at the end face of the optical fiber.
In our optical fiber arrays, the following technologies are adopted to minimize these losses.
- Sub-micron core position adjustment – Improved V-groove processing precision which allows for precise positioning of optical fiber cores.
- End-face polishing technology - PC/UPC/APC and other polishing methods are applied to reduce connection loss.
- Low-loss UV adhesives - Adhesives with excellent optical properties are used to suppress light scattering at the connection area.
Integrated LD/PD Waveguide and Fiber Array Devices
Optical communication systems require highly efficient connection between light emitting/receiving elements such as LD (laser diode) and PD (photodiode) and optical fiber. In particular, LD/PD array devices are becoming increasingly dense, and integrated devices using fiber arrays play an important role.
We manufacture fiber arrays that support direct fiber coupling to these LD/PD waveguides.
- High-density, narrow-pitch structures - fiber-to-fiber pitch is less than 125 µm, enabling high-density connection.
- Optical lead frame - Integrated structure of waveguide elements and optical fibers ensures positioning accuracy and stability.
- Low-loss coupling - Connector loss is kept below 0.1dB to maximize optical signal transmission efficiency.
Multi-Row Fiber Array (2-Row Type)
Next-Generation Fiber Array for High-Density Optical Connections
Our Multi-Row Fiber Array (2-Row Type) is a high-density optical connection device that uses ultra-precision processing technology to arrange optical fibers with high accuracy in both the horizontal (X) and vertical (Y) directions.
While maintaining the same mounting width as conventional single-row types (1D arrays), it increases channel density by up to 2x. This enables the high-density, high-precision optical connections required by next-generation optical technologies such as CPO (Co-Packaged Optics), ultra-high-speed optical transceivers, and multi-channel optical switches.
Key Features
±1.0um (depending on channel count and other specifications)
Through ultra-precision processing of V-groove substrates and micro-hole array technology, we achieve core pitch accuracy of ±1.0 µm (depending on channel count and other specifications). Positional deviation between rows is also strictly controlled, enabling low-loss connections with optical waveguide chips.
Future Development
Orbray is also developing a 3-row type fiber array to meet the growing demand for even higher density.
We will continue to provide highly integrated optical connection solutions for next-generation terabit-class optical communications and quantum information processing systems.
Our Unique Optical Lead Frame Technology
Orbray offers “optical lead frame” that integrate fiber arrays and waveguide elements. This lead frame integrates:
- Forming V grooves on a silicon or glass substrate
- Precise placement and fixing of optical fibers
- Direct coupling with LD/PD devices
Furthermore, the optical lead frame minimizes the connection distance between the LD/PD or silicon photonics device and the fiber array, thereby shortening the optical path length and minimizing losses. Narrow pitch arrays (pitch less than 100µm) and multi-channel configurations are also supported, making this design ideal for the latest coherent communication technologies and data center applications.
Bending Fiber Array
A bending fiber array is formed by a thermal process technique of the optical fiber to form a permanent bend within the fiber that can then be assembled into an array.
It is mostly used for the bonding and direct coupling to a SiP (Silicon Photonics) chip in small form factor module devices.
Narrow Pitch Fiber Array
The narrow pitch fiber array is a connection device made by our fiber etching technology and V-Groove Substrate processing technology. It is mostly used for the bonding and direct coupling to a SiP (Silicon Photonics) chip in small form factor module devices.
For a standard SMF fiber with 125μm clad diameter with a typical pitch of 250μm, we can taper and narrow the pitch to 50um by our fiber etching technology and mount within the V-Groove Substrate.
SMF is an optical fiber that transmits light in a single mode. It is widely used in telecommunications infrastructure because it minimizes signal distortion even over long distances, making it suitable for high-speed, high-capacity communication.
Fiber Array Bending, Angle Polishing, MPO Connector Assembly, Fiber Array with PMF and MCF in-line
* PMF（Polarization Maintaining Fiber）PMF optical fiber is specialized optical fiber designed to transmit light while preserving its polarization state. Due to its ability to suppress polarization distortions, PMF is used in applications requiring precise polarization control, such as laser systems, optical measurement instruments, interferometers, and various optical sensors.
Future Outlook
Advances in optical communication technology are accelerating the speed and density of coherent communications. In-line with this trend, the demand for connection accuracy and stability between optical waveguide elements and optical fibers is further increasing. In particular, fiber arrays with narrow pitch, low loss, and high stability are indispensable for next-generation optical communication standards such as 400G to 1.6T.
Orbray is developing products that will support even higher density and precision in the future by strengthening its proprietary ultra-precision processing technology, V-groove technology, and end-face polishing technology. This will contribute to higher performance and lower costs in next-generation optical communication systems.
Main Applications of Fiber Arrays
Fiber arrays are utilized across a wide range of fields as essential components supporting high-speed, large-capacity optical communications.
Data Centers & Communication Infrastructure
■ Optical Transceivers
Fiber arrays are used in optical transceivers that convert between electrical and optical signals within data centers and communication networks.
By arranging multiple optical fibers at high density, they enable ultra-high-speed communications at 100 Gbps, 400 Gbps, and even 800 Gbps.
■ CPO (Co-Packaged Optics)
CPO, which is gaining attention as a next-generation data center technology, integrates optical components with switch chips to reduce power consumption and improve transmission speed.
Fiber arrays play a critical role in providing the high-density optical connections between these optical components and chips.
Quantum Computers
In the practical implementation of quantum computers, methods that use light—such as photonic qubits—require precise control of multiple photons.
Fiber arrays enable stable input and output of optical signals to numerous qubits by providing high-precision, batch connections between optical waveguide chips and optical fibers. Since high-precision mounting with minimal positional deviation is required even in ultra-low-temperature environments, the ultra-precision processing technology of fiber arrays contributes to improving the scalability of quantum computers.
Optical Sensing & Measurement Instruments
In applications such as spectroscopic analysis equipment and multi-channel optical measurement systems—where optical signals from multiple wavelengths or multiple points are acquired and processed simultaneously—fiber arrays arrange multiple optical fibers with high density and high precision, achieving both miniaturization of equipment and improved measurement accuracy.
