A die having a regular polyhedral form, at least one opening face of the die being hinged to an adjacent hinge face such that the at least one opening face can be opened by pressing on at least one pressure face adjacent to the at least one opening face. The light emitting device includes a substrate, a first semiconductor layer on the substrate, a second semiconductor layer on the first semiconductor layer, and a multi-quantum well structure including at least one well layer and at least one barrier layer between the first and second semiconductor layers. The phase differences of the subsequences are calculated for frequency estimation using linear regression analysis.