(Reuters) - Finisar Corp reported first-quarter results that fell short of Wall Street expectations as the optical communication components maker continued to grapple with slowing demand in Europe and China, and forecast a weak second-quarter profit.

The company said it expects an adjusted profit of 12 cents to 16 cents per share for the second quarter, on revenue of $225 million to $240 million.

Analysts on average were expecting earnings of 19 cents per share, before items, on revenue of $236.2 million, according to Thomson Reuters I/B/E/S.

Slowing economic growth in China and the European debt crisis have forced customers to push back or cancel orders, weighing on the company's revenue since the start of this year.

For Finisar, which gets three quarters of its revenue outside the United States, the slowdown in demand continued to hurt first-quarter revenue which fell 3 percent to $220.5 million. Analysts expected revenue of $226.3 million.

The company also swung to a loss of $6.2 million, or 7 cents per share for the first quarter, from income of $10.1 million, or 11 cents a share, a year earlier.

Excluding items, the company earned 12 cents per share, falling short of analysts' estimates by 2 cents.

Finisar shares fell marginally following in trading after the bell. The stock closed at $13.52 on the Nasdaq on Tuesday.

(Reporting by Siddharth Cavale; Editing by Joyjeet Das)