No, it is your absolute right to ask for a pay raise as costs, life circumstances, your worth to the company - all of these have changed in the course of a year. There is nothing unprofessional about exercising your rights.
You just have to make sure you are doing it within the framework and policies of your workplace. Each company has a different incentive and compensation policies.
At a previous employer there was a fixed increase to cover general increases in expenses, called COLA (Cost Of Living Allowance) which everyone got irrespective of their performance or other increment.
There was also a grade bonus, and other allowances that were adjusted each year. This did not affect your base pay, but your overall income had a positive impact.
There was also a formal review / evaluation process; and you had a chance to discuss your performance ranking and incentive provided. There was an open an expected negotiation period.
At another job there was a more relaxed informal pay increment scheme (as this was a small company). At the end of the year, we had a company-wide recognition dinner; where high performers were recognized formally. This was also were major changes / promotions were announced. At the same organization, you were given multiple pay raises during the year; my first increase came immediately after my probation period (90 days); then I got a raise based on a specific project which was completed under budget and well before the scheduled deadline.
At each of these jobs I have approached personally and asked for a raise when I felt that I was not being compensated fairly based on my work or market conditions.
The key things that I learned the hard way:
Avoid talking in comparisons "Mr. X gets $$$$$ and I have more direct reports and should be compensated equally".
If you are going to dangle the threat of resignation, make sure to follow up on it. Otherwise you will have a hard time rebuilding the trust in the organization.
Related to the above, if the organization comes back with a counter offer when you use termination as a negotiating tactic, this is normally a sign that the organization is planning to let you go soon.
Be creative. Instead of asking for a raise in your base pay, ask for a higher contribution to a savings plan, or a higher travel allowance, an upgrade in benefits, etc. Know where the company is more receptive.
This may sound a harsh, but keep in mind that HR's primary role is to protect the company and not protect you, the employee. They are more than happy to reduce or maintain the payroll budget if you don't ask for a raise.
Don't be afraid to ask for what you believe is your right; be fair, be calm, and avoid having emotions sway the conversation and most importantly, understand the culture, practice and framework of your organization in order to understand how best to get the result you want.