An Overview Of Tunable Diode Laser Technology Development

Long wavelength (X > 22 μm) lead-salt diode lasers are useful for spectroscopy studies and also for long distance fiber-optical communications. Double heterojunction diode lasers have now been fabricated using a new material system, Pb 1-x Eu x Se y Te 1-y . These structures were grown lattice-matched to (100) oriented PbTe substrates by molecular beam epitaxy. Laser operation up to 190K pulsed, 147K CW, has been attained with up to 1 mW single mode output power. The growth of single quantum well lead-chalcogenide diode lasers will be described. The threshold current of these quantum well lasers increases relatively slowly with temperature, yielding CW operation up to 174K (at 4.41 μm wavelength), and pulsed operation up to 260K (at 3.97 μm). To achieve single mode operation, a simple technique has been developed for the fabrication of lead-salt C 3 (cleaved-coupled-cavity) diode lasers. The improvement in spectral purity and the reduction in threshold current of these coupled cavity lasers will be discussed.