The SLD1550P-A40 from Thorlabs Inc is a Superluminescent Diode with Wavelength 1530 to 1570 nm, Output Power 35 to 40 mW, Bandwidth (FWHM) 30 to 33 nm, Forward Voltage 1.4 to 1.8 V, Operating Current 750 to 900 mA. More details for SLD1550P-A40 can be seen below.