Assalam Alaikum,
Dear brother, I am 27 year old and working as a professor in engineering college. My question, is getting married compulsory, or if someone wants to stay single, will Islam allow this? It's my own personal question. Alham du little lah. I am much away from sins like any love relationship/Zina etc. I wish to do higher studies and somewhere I fear that I won't be able to concentrate on my career if I got married. Doing doctorate in engineering nearly takes five years, and might be it will be quite late for marriage, so as per the shariat, am I allowed to stay single?

Well yes I believe so. As long as you stay away from sinful acts such as premarital sex, falling in love with another girl before marriage, etc.