Answer the following questions: 1. What are the knee voltages (from the I-V curves) and the peak wavelength of each of the sources?

Answer the following questions: 1. What are the knee voltages (from the I-V curves) and the peak wavelength of each of the sources? Why do the I-V knees of the IR sources occur at lower voltages than visible sources? 2. Compare the L-I curves of the LEDs and the LD. Do the LEDs show any threshold current? What happens to the L-I curve of the LD at Ith? 3. Describe the output beam shapes of the different LED sources at various drive levels. How do you think the shape of the beams would affect the use of the source for different applications, say a free-space communication link, an indicator light, a sensor, etc.? 4. How does the output beam shape of the LD change from below to above threshold current? What causes this change? 5. How does the wavelength and lineshape of each source change as a function of drive current? Do LEDs and LDs behave the same or different? What is happening in the LD but not in the LEDs? 6. Assuming the exit slit for the LD you measured is 1 m x 10 m