Micro Grin Lenses for Precise Fiber Coupling & Beam Control
GRIN Lenses (Gradient-Index Lenses) feature a refractive index that gradually changes from the center to the edge, allowing exceptional control of light propagation within an ultra-compact form. This unique property enables precise focusing, efficient collimation, and seamless fiber coupling while minimizing system size.
Feature:
- Gradient-index profile ensures accurate focusing and low aberration
- Ultra-compact design for easy integration into dense optical systems
- High transmission with minimal insertion loss, supporting stable coupling
- Superior polishing and flatness for reliable performance in precision optics
- Flexible customization in sizes, lengths, and coatings for tailored applications
Application: Fiber optic communication, endoscopic imaging, laser collimation, miniaturized sensors, optical instrumentation, and other photonic systems requiring compact, high-performance optics.
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1. Unique Gradient Refractive Design
GRIN lenses feature a controlled variation of refractive index either radially or axially.
- Radial GRIN: Index decreases from center to edge, creating sinusoidal light propagation paths and self-focusing behavior.
- Axial GRIN: Index variation occurs along the optical axis, used for focal tuning and axial aberration compensation.
This gradient design eliminates the need for curved surfaces and enables compact, lightweight optical configurations.
2. Compact Structure & Material Versatility
Most GRIN lenses are cylindrical rods with diameters from 0.1–2 mm and lengths tailored to the optical period (P).
- Materials: Optical glass (e.g., modified N-BK7), silicon for infrared, or polymers like PMMA for low-cost applications.
- Fabrication Methods: Ion exchange (glass), diffusion, or precision polymer molding.
3. Optical Performance Highlights
- Self-Focusing without Curvature: Allows precise light control in 1D/2D without bulky lens stacks.
- Low Spherical Aberration: Ideal for high-performance, compact systems.
- Mode Field Matching: High coupling efficiency (>95%) with single-mode fibers.
- Beam Shaping: Converts beam profiles or compresses divergence in fast-axis laser collimation
4. Lens Types & Applications
| Type | Index Distribution | Length | Typical Use |
| Radial GRIN Lens | Parabolic radial gradient | P/4, P/2 | Fiber coupling, collimation, endoscopes |
| Axial GRIN Lens | Linear/nonlinear axial change | Adjustable | Aberration correction, extended focus systems |
| Selfoc Lens | Cylindrical with radial GRIN | 1–10 mm | Optical communication, compact imaging |
5. Application Areas
- Fiber Optics: Fiber-to-fiber coupling, isolators, DWDM multiplexers/demultiplexers
- Medical Endoscopy: Ultra-thin GRIN lens arrays for high-resolution micro-imaging
- Laser Systems: Beam shaping for marking/cutting or spot compression for LIDAR and sensors
- Sensing & Photonics: Enhanced signal collection in fiber-based strain/temperature sensing
| Parameter | Specification |
| Refractive Index Profile | Radial (parabolic), Axial (linear/nonlinear) |
| Material Options | Aluminosilicate glass, Silicon (IR), Germanium, PMMA (polymer) |
| Diameter Range | 0.1 mm – 2 mm |
| Length Options | Typically P/4, P/2, P (custom lengths available) |
| Numerical Aperture (NA) | 0.2 – 0.5 (depends on gradient and application) |
| Surface Quality | 40/20 to 20/10 (ISO 10110) |
| Surface Roughness | <1 nm RMS (for high-precision optical coupling) |
| Focusing Condition | L = P/4 → focuses light at output face |
| Wavelength Compatibility | UV to NIR (glass), 1–8 μm (silicon), adjusted by material selection |
| Transmission Efficiency | >95% (anti-reflection coatings available) |
| Applications | Fiber optics, laser systems, endoscopes, sensors, photonic chips |
