could not find driver for postgresql database in lumen 5.6

I am getting could not find driver for postgre database in lumen 5.6. But when i try this in my core php its working.

And this is my .env configuration data for postgre database

  DB_CONNECTION=pgsql
  DB_HOST=localhost
  DB_PORT=5432
  DB_DATABASE=test
  DB_USERNAME=xxxx
  DB_PASSWORD=xxxxxx

I tried the same configuration with laravel 5.6 and it works there.

Thanks in advance