Review Of State-Of-The-Art Lead-Salt Diode Laser Development

Long wavelength (λ > 22 pl) 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 l-x EuxSeyTe l-y . These structures were grown lattice-matched to (100) oriented PbTe substrates by molecular beam epitaxy. Laser operation up to 190 K pulsed, 147 K 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 174 K (at 4.41 μm wavelength), and pulsed operation up to 241 K (at 4.01 μm). To achieve single Nide operation, a simple technique has been developed for the fabrication of lead-salt C (cleaved-coupled-cavity) diode lasers. The improvement in spectral purity and the reduction in threshold current of these coupled cavity lasers will be discussed.