Calculation of laser diode wavelength:

From the theory of operation of semiconductor p-n junction, we know that:

      (1)

Where:

• h = Planck’s constant = 6.625x10^-34 [J*sec]
• l = Wavelength of the diode laser (670 ± 10) [nm] = (670 ± 10) x10^-9 [m].
• e = Electronic Charge (1.602x10^-19 [C]).
• c = Velocity of light (3x10⁺⁸ [m/sec]).
• V_turn-on = “Turn-on” voltage for Laser Diode or LED as determined from Figures 2 and 3 respectively.

Thus experimentally determined value of Laser Diode wavelength:

  =  ___________________ [m]

Rearranging this formula, the value of Plank's constant can be found.

Using LED

Experiment for determining the value of Planck’s constant using the LED was published in Ref. 2.

They used:

= ___________________ [J*sec]

= ________ %