Fiber Numerical Aperture Calculator
Calculate ideal step-index fiber numerical aperture, acceptance cone and V number.
YOUR CALCULATION
Result
—
Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Use a uniform step-index nonmagnetic fiber and distinguish the external acceptance angle from the internal material numerical aperture.
NA=√(ncore²−nclad²); sin acceptance=NA/noutside; V=π core diameter NA/λ0
Worked example
Core/cladding indices 1.48/1.46 give NA≈0.242487113. Doubling core diameter doubles V at the same wavelength and indices.
Assumptions and input details
Core index must exceed cladding. Geometrical acceptance ignores entrance Fresnel loss and mode coupling. The optional V²/2 mode count is only a large-V step-index approximation (shown for V≥10), not an exact mode solver or fiber suitability claim.
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Choose from 23 length definitions, including explicitly labelled regional measures. Area conversions square the length factor; geometric volumes cube it.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
Find reflected and refracted ray directions from incidence angle and two refractive indices. Detect total internal reflection and show the critical angle.
Calculate wave speed, frequency or wavelength from the other two. Convert units, find the period and view an illustrative normalized wave.
Calculate ideal Gaussian beam radius, Rayleigh length and divergence from the waist and wavelength.
Reserved advertising space.