Data on semiconductor laser amplifiers with a small tensile strain in the wells of multiple quantum well structures are presented. Semiconductor amplifiers with a small strain of 0.2% exhibit polarization insensitive characteristics with a signal gain of 15 dB in the 1.5 μm wavelength range. The enhancement of TM mode gain due to tensile strain is studied by measuring the dependence of amplified spontaneous emission spectra on device length and tensile strain.

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Polarization insensitive optical amplification was demonstrated in newly developed semiconductor optical amplifiers which have strained GaInAsP quantum well structures. We tailored the active region of the quaternary strained layer quantum well structure with small biaxially tensile strain of 0.2% in the well layers for polarization insensitive operation.

This letter describes 1.48 μm multiple quantum well (MQW) lasers with strained GaInAsP quaternary wells entirely grown by metalorgainic vapor phase epitaxy. The GaInAsP quaternary layers with 1.5% biaxially compressed strain showed an excellent crystal quality and an abrupt interface within half-monolayer fluctuations which was verified with photoluminescence spectroscopy. The maximum continuous wave output power of 140 mW was obtained at 20 °C with 1500-μm-long lasers whose facets were coated by anti- and high-reflection films. The small internal loss of 12 cm−1 and a high internal efficiency of 70% were obtained.