Each OP123 and OP124 device is a 935 nanometer (nm) high intensity gallium arsenide infrared emitting diode (GaAs), mounted in a miniature hermetically sealed “pill” package with an enhanced temperature range and a high power output. These devices are designed for direct mounting to PCBoards. Each OP223 and OP224 device is an 890 nm gallium aluminum arsenide infrared emitting diode (GaAIAs), mounted in a hermetically sealed “pill” package with an enhanced temperature range and a narrow irradiance pattern that provides high on-axis intensity for excellent coupling efficiency. These devices offer significantly higher power output than GaAs at equivalent drive currents and have a wavelength that is matched to silicon’s peak response. Their small package size permits high device density mounting. All these LEDs are mechanically and spectrally matched to the OP300 series, OP600 series and OP640 series devices.