Here is the result of lsblk for these disks:

sde                         8:64   0 931,5G  0 disk  
├─sde1                      8:65   0    40G  0 part  
│ └─md4                     9:4    0    40G  0 raid1
│   ├─systeme-swap        253:1    0     4G  0 lvm   [SWAP]
│   ├─systeme-var         253:2    0    15G  0 lvm   /var
│   └─systeme-chiffre     253:3    0    15G  0 lvm   
└─sde2                      8:66   0 891,5G  0 part  
  └─md5                     9:5    0 891,4G  0 raid1
    └─data-home           253:5    0   891G  0 lvm   /home
sdf                         8:80   0 931,5G  0 disk  
├─sdf1                      8:81   0    40G  0 part  
│ └─md4                     9:4    0    40G  0 raid1
│   ├─systeme-swap        253:1    0     4G  0 lvm   [SWAP]
│   ├─systeme-var         253:2    0    15G  0 lvm   /var
│   └─systeme-chiffre     253:3    0    15G  0 lvm   
└─sdf2                      8:82   0 891,5G  0 part  
  └─md5                     9:5    0 891,4G  0 raid1
    └─data-home           253:5    0   891G  0 lvm   /home

My idea is to stop the array, remove one disk and have this array in degraded mode with the other disk. Then plug a new disk (2Tb) on which I build a new array in degraded mode with all partitions and lvm needed. Then I transfer all the data from the remaining 1Tb disk to the new array, replace the 1Tb disk by a new 2Tb disk and then synchronize the new array.

Is it the good way to proceed? Or is there another better way?

Thank you for all advices.