Optical parameters of diode lasers based on an InAsSb/InAsSbP heterostructure

The rates of radiative recombination (including transitions induced by enhanced luminescence) and nonradiative recombination, internal quantum yield of luminescence, and the matrix element for band-to-band optical transitions were determined for the first time for InAsSb/InAsSbP diode lasers oscillating at wavelengths of 3.1–3.2 μm. It is established that the contribution of nonradiative recombination to the lasing threshold can be as large as 97%. The internal quantum yield of luminescence for the InAs_0.97Sb_0.03 compound is no higher than 3%. Most likely, the nonradiative channel is formed with involvement of Auger recombination with the constant C = 4.2 × 10^?38 m⁶s^?1 (T = 77 K). The studied samples of lasers feature relatively low optical losses ρ = 900 m^?1 and internal quantum efficiency of emission at the level of 0.6. The spontaneous lifetime of nonequilibrium charge carriers as determined from the radiative-recombination rate is equal to 6 × 10^?8 s, which is consistent with known published data.     

Interfacial and interband lasing in an AnAs/InAsSbP heterostructure grown by vapor-phase epitaxy from metal-organic compounds

Sources of coherent radiation are fabricated on the basis of a double InAs/InAsSbP heterostructure, grown by vapor-phase epitaxy from metal-organic compounds, that includes a thick (3.3μm) active region. The spectral characteristics of diodes with various cavity lengths are studied, and light polarization is measured. It is established that the modes that compose the spectrum of radiation are controlled by radiative recombination at the heteroboundary and in the bulk of the active region. A new mode with a wavelength of intermediate value, lying between the wavelengths of the aforementioned kinds of radiation, is observed if the current exceeds the threshold value by 30%. This intermediate mode presumably results from an interaction between the modes related to the interfacial and interband radiative recombination, which are present in the cavity at the same time.     

Distal 6p deletion syndrome: a report of a case with anterior chamber eye anomaly and review of published reports

We describe a 32 year old male with a distal 6p24.3-->pter deletion. He has specific developmental anomalies of the anterior chamber of the eye and a cleft uvula which is consistent with the recent localisation of genes for iris development and orofacial clefting to distal 6p. In addition he has progressive sensorineural deafness and this may localise a gene for deafness to this region. We conclude that a refined distal 6p deletion syndrome exists and includes a characteristic facial appearance with hypertelorism, downward slanting palpebral fissures, tented mouth, smooth philtrum, palatal malformation, ear anomalies, anterior chamber eye defects, progressive sensorineural deafness, cardiac defects, abdominal herniae, small external genitalia, and motor and speech delay.