uw to dbm

While we read the OpticalPower, host use dbm as unit , while snmp use uw, the relation as below:

Using the SNMPvalue of 790, and using units of tenths of microwatt,
790 becomes 79 microwatts or 0.079 milliwatts. Converting to dBm:
10 x log10(0.079) = -11.0 dBm

Sample:
*A:R119# show port 1/1/6detail
……
===============================================================================
Transceiver DigitalDiagnostic Monitoring (DDM), Internally Calibrated
===============================================================================
Value High Alarm HighWarn Low Warn Low Alarm
-------------------------------------------------------------------------------
Temperature(C) +47.3 +105.0 +100.0 -40.0 -45.0
Supply Voltage(V) 3.32 3.63 3.46 3.13 2.97
Tx Bias Current(mA) 4.5 12.0 10.0 2.0 1.0
Tx Output Power(dBm) -5.77 -1.00 -1.50 -10.00 -10.50
Rx Optical Power (avg dBm) -15.09 1.00 0.00 -16.99 -18.01
===============================================================================

With MIB walk as below:
…
22:tmnxDDMRxOpticalPowerLowWarning.1.35848192 (integer)200 #35848192 is ifindex of 1/1/6
23: tmnxDDMRxOpticalPowerLowAlarm.1.35848192(integer) 158
24:tmnxDDMRxOpticalPowerHiWarning.1.35848192 (integer) 10000
25:tmnxDDMRxOpticalPowerHiAlarm.1.35848192 (integer) 12589
…