以来

The word 以来 can be used with て form verbs or with nouns to refer to a specific time in the past. It usually translates as "since."

大学に入って以来、高校時代の友達に一度も会っていない。
Since I started college, I haven't seen my high school friends a single time.

携帯電話が登場して以来、街の公衆電話が少なくなった。
Since the introduction of cell phones, the number of pay phones in cities has decreased.

9/11以来、飛行機に乗る時のセキュリティチェックがとても厳しくなった。
Since 9/11, the security checks done when flying have become very strict.

父は10年前に亡くなった。それ以来、母は一人で私達兄弟を育ててくれた。
My father passed away before I was 10. Since then, my mother has raised my siblings and I by herself.