In the case of a 445 diode:
Total solar luminosity (3.846×10*26 W) divided by the surface area of the sun (6.0877×10*12 square km) yields 6330 W/square cm (calculated using WolphramAlpha).
Laser diode luminosity (1 W) divided by diode emitter surface area (50 μm) yields 2,000,000 W/square cm.