Crystal symmetry: 43m
Density: 4,3 g/cm^3
Optical spectral range: 0,53 - 16 mkm
Elastic constants 
: 10^11 dyn/cm^2 or 10^10 Pa)
| 14.12 | 6.24 | 6.24 | 0 | 0 | 0 |
| 6.24 | 14.12 | 6.24 | 0 | 0 | 0 |
| 6.24 | 6.24 | 14.12 | 0 | 0 | 0 |
| 0 | 0 | 0 | 7.04 | 0 | 0 |
| 0 | 0 | 0 | 0 | 7.04 | 0 |
| 0 | 0 | 0 | 0 | 0 | 7.04 |
Photolastic constants 
:
| -0.151 | -0.082 | -0.082 | 0 | 0 | 0 |
| -0.082 | -0.151 | -0.082 | 0 | 0 | 0 |
| -0.082 | -0.082 | -0.151 | 0 | 0 | 0 |
| 0 | 0 | 0 | -0.074 | 0 | 0 |
| 0 | 0 | 0 | 0 | -0.074 | 0 |
| 0 | 0 | 0 | 0 | 0 | -0.074 |
Refraction indices:
The values for refraction index for the given optical wavelengths.
| wavelength, mkm | refraction index |
|---|
| 0.55 | 3.4411 |
|---|
| 0.57 | 3.4012 |
|---|
| 0.6 | 3.3524 |
|---|
| 0.63 | 3.3132 |
|---|
| 0.66 | 3.2811 |
|---|
| 0.7 | 3.2462 |
|---|
| 0.8 | 3.183 |
|---|
| 0.9 | 3.143 |
|---|
| 1 | 3.1192 |
|---|
| 1.2 | 3.0844 |
|---|
| 1.4 | 3.0646 |
|---|
| 1.6 | 3.0509 |
|---|
| 1.8 | 3.0439 |
|---|
| 2.2 | 3.0331 |
|---|
| 2.4 | 3.0296 |
|---|
| 2.8 | 3.0236 |
|---|
| 3.2 | 3.0197 |
|---|
| 3.6 | 3.0166 |
|---|
| 4 | 3.0137 |
|---|
Sound velocity:
| direction | polarization | v (10^5 cm/s) |
|---|
| [110] | [110], L | 6.32 |
| [100] | S | 4.13 |
Gallium phosphide slowness surfaces in important planes
Acousto-optic figure of merit:
| sound dir. | sound pol. | light dir. | light pol. | M (10^-18 s^3/g) |
|---|
| [110] | [110] | -- | [110] | 44.6 |
| [100] | S | -- | arb. | 24.1 |
