This part is a kind of semiconductor called AMT128503T46L.

Function of this product has 1.25Gb/s Integrated 850nm MSM-TIA.

Manufacturers : ANADIGICS Inc

Image and pinout :

Some of the text within the PDF file :

AMT128503 1.25 Gb/s Integrated 850 nm MSM-TIA FEATURES · 1.25 Gb/s Differential Output TIA · 3.3V Operation · Automatic Gain Control · 850nm Photodetector with 100 mm x 100 mm Active Area · Integrated MSM detector & TIA · TO-46 Ultra Flat Window or Lens Package · TO-56 Ultra Flat Window Package APPLICATIONS · · Gigabit Ethernet (1.250Gb/s) Fibre Channel (1.0625 Gb/s) Data Sheet - Rev. 0 TO-46F Ultra Flat Window Package TO-46L Lens Package TO-56F Ultra Flat Window Package PRODUCT DESCRIPTION The ANADIGICS AMT128503 is a 3.3V monolithically integrated Metal-Semiconductor-Metal (MSM) photodetector and transimpedance amplifier (TIA) used to convert an 850nm input optical signal into a differential output voltage, and is manufactured in ANADIGICS’ 6” GaAs wafer fabrication facil [ ... ]

AMT128503T46L PDF Datasheet Download