If there are no media present in the optical disk drive e.g. ODD, the OS turns off the power to the optical drive. This is called ZPODD.
To revert to always-on status, turn off this functionality in the Registry:
Go to ZeroPowerODDEnabled.
If it's type is DWORD (32 bit), and value is 0, ZPODD is disabled; if it’s any other value, ZPODD is enabled.