ONET1131EC: can you help explain below two question about EML laser driver

Kevin-Cheng

Part Number: ONET1131EC

Hi Team,

I have two question about below schematic,

1. for the EML TOSA, it has three diodes, Laser diodes are used to emit lasers; PD is used to detect laser emission power; what is the use of other one?

2.I see two structures of the below schematics are EML type, we know EML bias need negative voltage; does it mean for figure 48, we need two negative voltage for EML bias and PD driver; for figure 49, we just need one negative voltage for bias ?

kevin

over 6 years ago

0 Nasser Mohammadi over 6 years ago

TI__Guru* 93670 points

Hi Kevin,

1). The third diode is used for biasing the EML laser so it can emit light. Based on EML part, different supply (5V or 3.3V) could be used.

2). Your understanding is correct. Please note this all depends on the EML laser.

Regards,, Nasser

0 Kevin-Cheng over 6 years ago in reply to Nasser Mohammadi

TI__Expert 3135 points

Hi Nasser,

Could you please help to check whether the mark on below picture is correct ?

Kevin

0 Nasser Mohammadi over 6 years ago in reply to Kevin-Cheng

TI__Guru* 93670 points

Hi Kevin,

You understanding is correct. As laser edges or across temperature, there could be laser power stability. PD feedback is used to maintain power across these different factors.

Regards,, Nasser

Interface

Interface forum

ONET1131EC: can you help explain below two question about EML laser driver