Fabrication and characterization of 1 550 nm polarization-insensitive semiconductor optical amplifiers

A 1550 nm polarization-insensitive semiconductor optical amplifier (SOA) was fabricated with InGaAs tensile-strained bulk active region. Beam propagation method and planar wave expansion method are used to calculate the mode field profile and the mode reflectivity. For the SOA with a buried waveguide deviated 70 from the normal direction of cleaved mirrors, the thickness tolerance of the mirror is 3% for keeping the reflectivity of TE mode and TM mode less than 10−4 simultaneously. For a SOA with a cavity length of 800 μm, the polarization sensitivity of amplified spontaneous emission spectra is less than 0.5 dB at an injection current of 250 mA, the corresponding fiber-to-fiber gain is 11.9 dB at 1550 nm with a 3 dB bandwidth of 63 nm, and the saturation output power is 5.6 dBm. The noise figure shows 8.8 and 7.8 dB at 1550 and 1570 nm, respectively. For a packaged SOA with a cavity length of 1000 μm, the fiber-to-fiber gain is 15 dB at an injection current of 190 mA.