ULTRA NARROW LINEWIDTH OPTICAL SOURCE

THIS PROPOSAL DESCRIBES AN EFFORT TOWARDS DEVELOPING AN OPTICAL SOURCE THAT WILL BE USEFUL IN PHOTONIC SYSTEMS. THIS SOURCE SUBSYSTEM IS BASED ON A SEMICONDUCTOR INJECTION LASER THAT IS PLACED IN A SPECIFICALLY DESIGNED EXTERNAL CAVITY. THE LENGTH OF THE EXTERNAL CAVITY IS 1.5 CM, CORRESPONDING TO A ROUND TRIP TIME OF 100 PS. THIS MAKES IT POSSIBLE TO DIRECTLY MODULATE THE LASER AT RATES OF UP TO SEVERAL GHZ WITHOUT ADVERSE EFFECTS DUE TO MODE-LOCKING. EXPECTED LINEWIDTH OF THE SOURCE IS LESS THAN 50 KHZ. IN ORDER TO ASSURE STABLE OPERATION AND ELIMINATE THE SUSCEPTIBILITY OF THE SOURCE TO SPURIOUS REFLECTIONS, MECHANICAL VIBRATIONS AND THERMAL VARIATIONS, THE LASER CHIP FACET FACING THE EXTERNAL CAVITY IS ANTI-REFLECTION COATED, AND ALL THE COMPONENTS COMPRISING THE SOURCE SUB-SYSTEM (LASER CHIP, LENS, WAVELENGTH SELECTIVE ELEMENT, AND MIRROR) ARE PERMANENTLY CLAMPED ONTO A SINGLE RIGID PACKAGE-ELEMENT.