What Is the Optical Fiber Numerical Aperture (NA) & V-Number Calculator?
The V-number is a dimensionless parameter that characterizes the waveguiding properties of an optical fiber.
How Does the Optical Fiber Numerical Aperture (NA) & V-Number Calculator Work?
Combines refractive index contrast, core diameter, and wavelength to solve Maxwell modal boundary conditions.
Optical Fiber Numerical Aperture (NA) & V-Number Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
ext{NA} = sqrt{n_1^2 - n_2^2}, quad V = rac{2pi a}{lambda} ext{NA}, quad V < 2.4048 implies ext{Single-Mode}
Step-index fiber waveguiding numerical aperture and modal cutoff parameter.
How to Use the Optical Fiber Numerical Aperture (NA) & V-Number Calculator
- Input core and cladding refractive indices, core radius in micrometers, and operating wavelength.
Step-by-Step Example Calculation
Standard SMF-28 Telecom Fiber
Input Values:
coreRefractiveIndex:1.448
claddingRefractiveIndex:1.443
coreRadiusUm:4.1
wavelengthNm:1550
Worked Steps: NA = 0.1202, V = 1.998 (< 2.405), confirming single-mode operation with cutoff at 1288 nm.
Understanding Your Result
Indicates whether only one mode (HE11) propagates or multiple modes propagate, and shows cutoff wavelength.
Factors That Affect the Result
- Doping silica with germania raises the core index, increasing NA and mode confinement.
When Should You Use This Calculator?
- Telecommunications optical network design, fiber optic sensor specification, and laser pig-tailing.
Assumptions & Limitations
- Assumes circular step-index core profile; graded-index fibers require parabolic profile correction.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Standard dielectric waveguide modal cutoff theory.