More than just vacationers are heading to points across the globe for summer holiday. Technology investors are, too.

With the increasingly global nature of the technology market, many portfolio managers have found winners among far-flung companies. Favorite growth areas include optical networking and wireless infrastructure plays. But while tech plays in Europe, Asia and the Middle East have attracted U.S. investors, the road ahead may get bumpy at times.

"Technology is an area that I want to be in," says financial adviser Robert Markman of Minneapolis. "I don't care that

Ericsson

(ERICY)

is a Swedish company or that

Nokia

(NOK) - Get Report

is Finnish."

Certainly, Nokia and Ericsson have attracted investor attention. Ericsson is up 37% this year, and Nokia is up 14.4%. But portfolio managers are looking beyond those household names to come up with ideas for the next wave of international investing.

International tech companies are "the area of growth in the future, but along the way, there's going to be a lot of volatility," cautions Scott Wells, a financial adviser with

Evensky Brown & Katz

in Coral Gables, Fla.

Vincent Willyard, portfolio manager of the

(DHIIX)

Duncan-Hurst International fund, looks at the technology landscape quite differently. His $40 million fund has about a 55% weighting in technology because of his fondness for telecommunications, where he's emphasizing wireless infrastructure and optical networking.

To that end, Willyard hasn't gone far from home for

Nortel Networks

(NT)

, the Canadian Internet and wireless infrastructure company that's advanced 56.1% this year alone.

Those same trends hold true in Europe and the Pacific Rim, Willyard says. He likes British optical-network provider

Bookham Technologies

(BKHM)

. In Japan, he's picked up

Furukawa Electric

, which makes optical components and had owned as much as 20% of U.S. fiber-optics superstar

JDS Uniphase

(JDSU)

before it began selling some of its stake.

Jiyoung Kim, co-manager of the

(PAIVX)

Pimco Global Innovation fund, says she's holding on to her positions in Nokia and Ericsson because they're big global players. Ericsson, for example, could be a good play in China's telecommunications infrastructure, she says.

But Kim says she has trimmed international holdings a bit and put money to work closer to home because of concerns about European wireless.

Similarly, Richard Begun, portfolio manager of the

(ORGAX)

Orbitex Growth fund, says there have been compelling reasons to stay in the U.S. Last spring's

Nasdaq selloff slashed

price-to-earnings ratios and brought American companies' valuations more in line with their European counterparts.

Begun says he's still interested in opportunities in Europe, simply because the potential is huge. "Internet and Internet infrastructure

are two to three years behind the U.S," he says. "This is the time to start thinking about buying those companies."

Though he's cut his international holdings to represent just 3% of his overall portfolio, Begun is a big believer in fiber optics; he likes Bookham and supply-chain software provider

Kewill Systems

, both British. Begun likes some Internet stocks, though some other portfolio managers are shying away from them. One of the stocks he's looking at is

Pacific Century CyberWorks

(PCCLF:OTC BB), a Hong Kong company that's working on business-to-business exchanges.

Begun and other managers wax euphoric about the potential for wireless in China. With a penetration rate of less than 3%, the mainland is poised for an incredible surge in usage.

"Even if you're talking about 50,000 to 60,000 new subscribers, that's pretty meaningful," Kim of Pimco says. For that reason, she likes China Mobile, the wireless spinoff of

China Telecom

.