How to force Laravel to generate https link?

I am using cloudflare CDN to "supercharged" my site and I am using it's full SSL for better security for my site. However, I am frequently experiencing error 523 on my site. I have consult help for both cloudflare and hosting company, but both were saying no problem with their side. So, I have to do my own experiment try to fix the problem.

Now, I try to make the full SSL to flexi SSL. Because the connection between server and Cloudflare were done with insecure connection (http), therefore the generated link by laravel all are in http format. This brings problem that all my CSS & JS doesn't load on Firefox and return with the error saying Blocked loading mixed active content.

So, how can I force Laravel to generate URL with the https connection?

via Chebli Mohamed