How to use the laser cavity mode spacing calculator
Find the frequency gap between longitudinal modes of a laser cavity. Enter cavity length, refractive index in cavity in the fields above; the mode spacing are computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “laser mode spacing”, “free spectral range”, “laser cavity frequency gap”, “calculate laser cavity mode spacing”, “find mode spacing”.
Formula
Variables
- L — Cavity length (m)
- n — Refractive index in cavity
Worked example
With cavity length = 0.3 m, refractive index in cavity = 1, the calculator gives mode spacing ≈ 499.6541 MHz; mode spacing ≈ 0.4996541 GHz.
Frequently asked questions
What is the laser cavity mode spacing calculator used for?
Find the frequency gap between longitudinal modes of a laser cavity. It helps with questions such as “laser mode spacing”, “free spectral range”, “laser cavity frequency gap”.
What is the formula for the laser cavity mode spacing calculation?
Mode spacing (MHz) = CLIGHT / (2 × L × n) / 1e6. Mode spacing (GHz) = [Mode spacing] / 1000. Here L is cavity length (m), n is refractive index in cavity.
What inputs do I need for the laser cavity mode spacing calculator?
You need cavity length in m, refractive index in cavity. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the laser cavity mode spacing calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the laser cavity mode spacing result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.