This part is a kind of semiconductor called GK152.
Function of this product has Slot Optical Switch.
Manufacturers : TAT ELECTRONICSCO
Image and pinout :

Some of the text within the PDF file :
Package Dimensions : GK152 TAT ELECTRONICSCO.,LTD 2.15 6 0.2 4+ - 0.1 0.3 12.2 + - 0.3 1.5 3.5 12.2 ± 0.3 0.2 4.0 + - 0.1 6.0 2.85 7.15 6.65 0.5 10.0 φ 3.6 ± 0.5 6.0 http:/// 12.0MIN. 0.4 - 0.3 0.1 + 0.4 (2.54) 12.0 18.2 + 0.3 - 0.1 (8.6) 4 1 Internal connection diagram (Common to 4 models ) 1 4 1 2 3 4 2 3 2 3 Anode Cathode Collector Emitter GK152 [ ... ]
GK152 PDF Datasheet Download
