In some cases, the 'show interfaces diagnostics optics <interface-name> ' command does not display an output:

root@R1-RE0> show interfaces diagnostics optics ge-5/3/2
root@R1-RE0>

The corresponding small form-factor pluggable (SFP) driver does not support Digital Diagnostics Monitoring (DDM):

NPC5(R1-RE0 vty)# show sfp 13
 
SFP driver state:
index: 13
  vector: 0x4235ded0, pic context: 0x4fea36d8, sfp name: 'MIC(5/3)' , pic arg: 2
  type: 1, present: 1, id memory scanned: 1 delay count 0
  change: 0, failure count 0, diags enabled: 0, diags polling count = 0, no diags polling from RE = 1
  eeprom read time:  35 ms, diagnostics read time:   0 ms
SFP capability register values
  diags implemented: 0, diag alarms implemented: 0 <-- No Diags Implemented
  addr change required: 0, int calibration: 0, ext calibration: 0
Linkstate: UP
 
 
ID:                  0x03
   Extended ID:         0x04
  Connector type:      0x07
   Transceiver type:    0x02
   SFF-8472 compliance: none -- no DDM, no wavelength <-- Also not SFF compliant, which is required for diagnostics monitoring.
   Wavelength           1310 nm
   Fiber mode           SM
   I2C write delay:     400 us
   Tunable:             False
 

This is a product limitation of the SFP in use and cannot be fixed. Use small form-factor pluggable (SFP) drivers that support Digital Diagnostics Monitoring (DDM).