I am looking for

PN: SI-B8R171550WW
Link for reference: SI-B8R171550WW Samsung Semiconductor, Inc. | Optoelektronik | DigiKey

I want to know right alternative

and i want to know difference between SI-B8R171550WW and SI-B8R171560WW


Comparing SI-B8R171550WW and SI-B8R171560WW, I only found a slight difference in dimensions–the 550 and 560 codes refer to length (see datasheets for details). The 560 version also had two maximum values added in the performance specs, but these were the same as the nominal value, so nothing actually changed.

Datasheet: c9-SI-B8T111550WW.pdf (678.3 KB)
Datasheet: c1-SI-B8R151560WW.pdf (603.1 KB)

Both of these products are obsolete, but SI-B8R171560WW still had some stock available at the time of this post. The EOL notice suggested part number SI-B8R113560WW as a replacement for both of them. I posted all of the information that I could find for that product, below. There are a few electrical differences, but perhaps not enough to be critical. It would depend on your application.

EOL Notice: [click here ].
SI-B8R113560WW Product Page: [click here ]
Datasheet: 13-SI-B8T172560WW.pdf (1.6 MB) The document title implies only one part number, but many are included in the file.