LightRun Popularization: Fiber Collimators —
Precision Navigator of Optical Signals - Parameter Analysis and Production Applications

Amid the continuous iteration and upgrading of optical communication and laser technologies, fiber collimators, as core passive optical components ensuring the stability of optical signal transmission and the precision of regulation, play a pivotal role in the process of optical signal transmission and processing. This article will focus on the key performance parameters of fiber collimators and their typical application scenarios across various industries, while sharing the core technological advantages of Guangcheng in the R&D and manufacturing of fiber collimators.

(I) Key Performance Parameters of Fiber Collimators

As a core optical component in optical communication and laser application systems, the performance of a fiber collimator directly affects transmission efficiency, beam quality, and overall system stability. This section analyzes its key performance indicators.

1. Insertion Loss (IL)

(1) Definition:Insertion Loss refers to the attenuation of optical power as the signal passes through the collimator, caused by factors such as optical design imperfections, alignment errors, and material absorption. It directly indicates the level of energy loss during transmission. Low insertion loss effectively reduces signal attenuation and ensures stable optical transmission.

(2) Calculation Formula
(Where Pin is the input optical power and Pout is the output optical power.)

(3) Key Parameters

Alignment Accuracy:
The coaxial deviation between the fiber core and the lens optical axis (typically ≤1 μm), as well as the matching accuracy between the lens focal length and the distance to the fiber end face.

Lens Quality:
The lens surface flatness should reach better than λ/20, with good refractive-index uniformity, and a transmission rate ≥99.5%.

2. Return Loss (RL)

(1) Definition:Return Loss refers to the ratio of the optical power reflected back to the light source—after reflection from various optical interfaces within the collimator—to the incident optical power. It is used to quantify the level of optical reflection and is critical for ensuring the stability of the light source.

(2) Calculation Formula
(Where Pin is the input optical power and Pr is the reflected optical power.)

(3) Technical Requirements

Physical Contact (PC) End Face:
A typical requirement is ≥55 dB, suitable for optical modules that are not highly sensitive to back-reflection, such as traditional SDH equipment.

Angled Physical Contact (APC) End Face:
With an 8° or 9° angled design that directs reflected light away from the original optical path, the requirement is ≥65 dB. This type is commonly used in back-reflection-sensitive scenarios such as high-power lasers and DWDM systems.

3. Working Distance (WD)

(1) Definition:Working Distance refers to the axial distance from the optical end face of the collimator (typically the outer surface of the lens) to the beam waist, where the beam diameter reaches its minimum.

(2) Calculation Formula
(Where ω₀ is the beam waist radius and λ is the optical wavelength.)

(3) Parameter Requirements

If the distance between two collimators is shorter than the working distance, the beam has not yet reached its waist, and the spot size has not reached its minimum, which can easily lead to increased coupling loss.

If the distance exceeds the working distance plus the Rayleigh range, the beam divergence becomes significant, and the spot size may surpass the tolerance range of the receiving end, likewise causing higher loss.

4. Beam Diameter

(1) Definition:Beam diameter refers to the spot diameter at the working distance where the optical intensity drops to 1/e² (≈13.5%) of its peak value. This definition aligns with the Gaussian beam intensity profile and is the standard measurement method widely used in the industry.

(2) Calculation Parameters

D_beam: Diameter of the collimated beam (measured at the 1/e² intensity point).

λ: Laser wavelength, typically expressed in micrometers (µm) or nanometers (nm).

f: Focal length of the collimating lens, usually in millimeters (mm).

ω₀: Beam waist radius of the incident beam (at the 1/e² intensity point), expressed in the same units as f.

D₀: Incident beam diameter at the lens (at the 1/e² intensity point), where D₀ = 2ω₀. This value is typically easier to measure or obtain from the laser’s specification sheet.

(3) Parameter Requirements

The smaller the beam diameter, the higher the requirements for the coaxiality and angular deviation between the two collimators, resulting in a narrower tolerance range.

The larger the beam diameter, the greater the allowable deviation during alignment, making system assembly correspondingly easier.

5. Collimation Degree / Beam Divergence Angle
(1) Definition: Collimation is usually quantified by the far-field divergence angle (full angle θ). It reflects the rate at which the beam diameter increases with transmission distance away from the waist, which essentially describes the spatial divergence characteristics of a Gaussian beam.

(2) Calculation Formula: (ω₀ is the beam waist radius, λ is the wavelength of light)

(3) Parameter Requirements

The smaller the divergence angle, the higher the “pointing accuracy” of the beam and the better the collimation. A low divergence angle ensures that the beam maintains a relatively small spot size even after long-distance propagation, making it a key indicator of collimator performance.

(II)Application Scope of Fiber Collimators
Fiber collimators, with their high precision and low loss advantages, have been widely adopted in multiple fields including optical communication, laser processing, testing and measurement, optical sensing, and imaging.

1. Combination of Fiber Devices and Free-Space Optical Devices
The input/output ports of acousto-optic modulators and inline isolators require symmetric coupling via collimators. In high-demand scenarios, the individual collimator’s output efficiency must reach 99%, coupling efficiency must reach 95%, and it must have sufficient back-reflection resistance and be able to handle high output power.

2. Laser Processing Field
Thanks to their excellent beam collimation performance, fiber collimators enable high-precision, high-quality metal cutting, precise drilling on various materials, and stable, highly collimated laser sources for additive manufacturing (3D printing). They are suitable for all scenarios requiring high-precision laser processing.

3. Optical Device Testing and Measurement
In the development, production, and quality inspection of optical devices, fiber collimators are core calibration and testing tools. They can precisely control beam parameters, simulate real optical signal conditions, and measure key performance metrics of optical devices (such as collimators, optical couplers, and gratings), including divergence angle, working distance, and loss. This provides data support for device optimization and standardized production.

4. Optical Sensing and Imaging

Optical Sensing: Facilitates bidirectional transmission between sensing signals, optical fibers, and sensors, reducing signal loss and improving the sensitivity and response speed of sensing systems.

Optical Imaging: In industrial inspection and medical imaging, fiber collimators ensure stable transmission of optical signals to imaging systems, enabling real-time monitoring and imaging, and enhancing image clarity and resolution.

(III) Advantages of LightRun Optoelectronics in Fiber Collimators

As a high-tech enterprise focused on the optical communication field, LightRun Optoelectronics possesses comprehensive and significant advantages in the production, manufacturing, and service support of fiber collimators:

1. Full-Process Quality Control
Through advanced manufacturing processes and precision equipment, from the selection of high-performance materials for patch cords and lenses to meticulous machining and assembly, we achieve high-precision positioning and high-quality packaging of fiber collimators. Rigorous material selection and process control ensure stable and reliable product performance, seamlessly meeting the demands of high-precision processing scenarios such as metal cutting, material drilling, and 3D printing.

2. Customized Solutions
We provide tailored fiber collimator solutions, designing products according to customers’ specific application scenarios and technical requirements in the laser processing field. Our collimators can be customized with different beam quality, working distance, and wavelength compatibility.

3. High Product Compatibility
Our product designs fully consider industry equipment compatibility, ensuring seamless integration with a wide range of mainstream fiber lasers and laser processing auxiliary equipment. This allows customers to integrate our products without major modifications to their existing production systems, reducing both system upgrade costs and time.

4. Strict Quality Assurance
We have established a comprehensive quality management system throughout the entire process. From raw material selection to final product delivery, each key procedure undergoes strict inspection and screening. This fundamentally ensures consistent performance and long-term reliability of our fiber collimators, while providing customers with solid product guarantees and after-sales support.

With the rapid evolution of optical communication systems toward higher capacity and faster speeds, the technical requirements for industrial-scale fiber collimator manufacturing are becoming increasingly demanding. LightRun Optoelectronics has consistently risen to the challenge, adhering to the philosophy of “technological breakthrough, quality perseverance” to provide global customers with high-quality, comprehensive fiber collimator solutions. We sincerely invite more industry partners to join us in exploring new frontiers in optical communication technology.