Fiber Optic Collimator
Product Overview
A fiber optic collimator is a key passive device that converts divergent light from an optical fiber into collimated (parallel) light for free‑space propagation, or couples external parallel light back into the fiber efficiently. Its core function is to bridge the interface between fiber‑based and free‑space optical paths.
Operating Principle
In simple terms, its operation is based on the focusing property of lenses:
- Collimating Mode (Fiber → Free Space): The fiber end face is precisely positioned at the focal point of the internal lens. The divergent light emerging from the fiber is refracted by the lens and transformed into a beam with very small divergence angle (collimated light).
- Coupling Mode (Free Space → Fiber): This process is completely reversible. Parallel light from free space passes through the same lens and is accurately focused onto the fiber end face, coupling efficiently back into the fiber.
Classification
Fiber collimators can be classified along several dimensions:
1. By Lens Type
C‑Lens: Simple structure, low cost, widely used in compact optical communication components such as isolators and circulators.
G‑Lens (Gradient‑Index Lens): Compact in size, using its ¼ pitch (0.25 Pitch) characteristic to achieve collimation. Together with C‑Lens, it is one of the two core lenses in miniature devices.
- Aspheric Lens: Effectively eliminates spherical aberration, providing near‑diffraction‑limited spot quality, suitable for high beam quality requirements.
- Achromatic Lens: Composed of multiple lens elements to correct chromatic aberration, ensuring that different wavelengths focus at the same point, suitable for broadband light sources.
2. By Adjustment Function
- Fixed: Pre‑aligned at the factory with fixed focal length, offering compact size, low cost, and high stability.
- Adjustable: Allows users to manually adjust the distance between the fiber and the lens to change beam size or waist position, providing flexibility.
3. By Fiber Mode
- Single‑mode Fiber Collimator (SM): Good beam quality and small divergence angle, the mainstream choice for telecom‑grade applications.
- Multi‑mode Fiber Collimator (MM): Larger core diameter, capable of coupling more optical power, but with relatively poorer beam quality.
- Polarization‑Maintaining Fiber Collimator (PM): Uses PM fiber internally to maintain the polarization state of light, essential in fiber lasers, coherent communications, and related fields.
Features
1. Low Insertion Loss
2. High Return Loss
3. Excellent Environmental Stability and Reliability
Applications
1. Optical Communication Systems: As a fundamental building block for optical isolators, circulators, optical switches, wavelength division multiplexers (WDM), etc.
2. Fiber Lasers and Amplifiers: For beam collimation, coupling, and polarization management.
3. Fiber Optic Sensing: Enhances sensor sensitivity in fiber sensing systems.
4. Research and Laboratories: For beam collimation, splitting, beam expansion, and coupling free‑space light into spectrometers and other fiber‑based instruments.
Technical Specifications
(The following parameters are for Single‑mode Fiber Collimators)
| Parameter | Grade P | Grade A |
| Wavelength(nm) | 1310±30nm,1550±30nm | |
| 1310/1550±30nm,980/1550±30nm or customer-specified | ||
| Insertion Loss (Typ.)（dB） | 0.17 | 0.2 |
| Insertion Loss (Max.)（dB） | 0.2 | 0.25 |
| Return Loss (Typ.)（dB） | 65 | 60 |
| Beam Diameter(mm) | <0.5 | |
| Operating Temperature(℃) | -20℃∽＋75℃ | |
| Storage Temperature(℃) | -40℃∽＋85℃ | |
| Package Dimensions | 3.2×9 or 10mm gold-plated tube, or 2.78×9mm glass tube, or customer-specified | |
| Fiber Type | 250μm bare fiber or 900μm tight buffer | |
Required Working Distance
| Lens Type | Wavelength | Grade | Working Distance | Pigtail Type | Fiber Length | Package | Fiber Type | Connector |
| SCL=C- Lens | 13=1310nm | P=Grade P | 05=5mm | B=250um bare fiber | A=1.0m | A=3.2×9 or 10mm gold-plated tube | 0=SMF-28 | 0=NO |
| SGL=G-Lens | 14=1480nm | A=Grade A | 06=6mm | L=900um tube | B=1.5m | B=2.4×10mm stainless steel tube | 1=50/125μm | 1=FC/APC |
| 15=1550nm | 07=7mm | C=2.0m | C=1.4×8mm glass tube | |||||
| 35=1310/1550nm | 08=8mm | S=specified | D=2.78×9mm glass tube | 2=62.5/125μm | 2=FC/PC | |||
| 09=9mm | E=1.3×8mm gold-plated tube | 3=105/125μm | 3=SC/APC | |||||
| 10=10mm | 直径 1mm G-lens, C-lens 准直器 | 4=SC/PC | ||||||
| …… | E=1.8×8mm gold-plated tube | 5=ST | ||||||
| 70=70mm | 直径 1mm G-lens, C-lens 准直器 | 6=LC |
Required Spot Size
| Lens Type | Wavelength | Grade | Beam Diameter | Pigtail Type | Fiber Length | Package | Fiber Type | Connector |
| SCL=C- Lens | 13=1310nm | P=Grade P | 1=100μm | B=250um bare fiber | A=1.0m | A=3.2×9 or 10mm gold-plated tube | 0=SMF-28 | 0=NO |
| SGL=G-Lens | 14=1480nm | A=Grade A | 2=200μm | L=900um tube | B=1.5m | B=2.4×10mm stainless steel tube | 1=50/125μm | 1=FC/APC |
| 15=1550nm | 3=300μm | C=2.0m | C=1.4×8mm glass tube | |||||
| 35=1310/1550nm | 4=400μm | S=specified | D=2.78×9mm glass tube | 2=62.5/125μm | 2=FC/PC | |||
| 53=1530nm | 5=500μm | E=1.3×8mm gold-plated tube | 3=105/125μm | 3=SC/APC | ||||
| …… | 6=600μm | 直径 1mm G-lens, C-lens 准直器 | 4=SC/PC | |||||
| …… | E=1.8×8mm gold-plated tube | 5=ST | ||||||
| 10=1000μm | 直径 1mm G-lens, C-lens 准直器 | 6=LC |
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