## How do you calculate grating constant?

The formula for diffraction grating: Obviously, d = \frac {1} { N }, where N is the grating constant, and it is the number of lines per unit length. Also, n is the order of grating, which is a positive integer, representing the repetition of the spectrum.

### What is a grating coupler?

An example of guided-mode resonance is a grating coupler, which is a region on top of or below a waveguide where there is a grating. Off-resonance light incident on the grating behaves almost the same as it would if it was incident in an area where there is no grating.

**What is ruled grating?**

A ruled grating is produced by physically forming grooves on a reflective surface by using a diamond tool mounted on a ruling engine. The distance between adjacent grooves and the angle they form with the substrate affect both the dispersion and efficiency of the grating.

**How do you calculate grating spacing?**

This can be represented by the equation: d = 1/N where N = the number of groves per unit length (in this case, millimeters) From the diagram above, we see ‘d’ is the grating spacing, and ‘θ’ is the angle of diffraction.

## What is a grating element and how its value is calculated?

Grating element is equal to the reciprocal of number of lines per cm on grating. Let a train of plane waves be incident normally on grating. Considering light rays passing through the grating straight will be conveyed at ‘P’ As the wavelets through the various slits reach the point ‘p’ after covering equal distance.

### What is EDGE coupling?

An edge coupler based on multi-stage tapers consists of multiple unidirectional tapers in different layers with their wide end near the fiber and narrow end close to successive photonic waveguides.

**How do you calculate groove spacing?**

Usually, gratings are specified by their groove frequency given as number of grooves per millimeter. The groove spacing in nanometers is then found by taking the reciprocal of the groove frequency, and multiplying by 106.