When the Berlin Wall fell in November 1989, Klaus Berka was a 40-year-old engineer working for VEB Carl Zeiss, a vast conglomerate owned by the East German state that dominated the small city of Jena. Mr Berka had watched in frustration as the company, which manufactured optical equipment and semiconductors and had been internationally competitive until the 1960s, fell further and further behind businesses in the west.
Within a few months of the fall of the Wall, the company had collapsed and many of Jena's best and brightest moved to West Germany or abroad. But Mr Berka decided to stay in the town. "I thought, 'Why don't we try and do something right here?'," he remembers. "It was a chance to realise all the dreams we hadn't been able to realise in the GDR."
In May 1990, Mr Berka and two colleagues quit Zeiss and, with seed capital of just 6,000 East German marks, set up Analytik Jena, a new company. Initially, it supplied products to companies in central and eastern Europe that had been clients of Zeiss. Early success meant it was soon able to acquire what remained of a research and development unit of Zeiss and began to develop its own products, starting with measurement tools for the environmental and pharmaceutical industries. The company went public in 2000 and now employs 800 people and has a market capitalisation of €45m ($67m, £41m).
The success of Analytik Jena is emblematic of the resurgence of Jena - one of the few places where Helmut Kohl's post-reunification promise of "blooming landscapes" in the former East Germany has become a reality. In fact, the university town in the south-eastern German state of Thuringia is a thriving high-tech hub.
From industrial giants like Jenoptik and Schott to start-ups like Analytik Jena and CyBio, Jena-based companies are at the cutting edge of developments in optoelectronics and biotechnology. In fact, Jena now has seven listed companies, impressive for a small city of 100,000 people that was part of a planned economy just two decades ago.
Jena now looks and feels much like an affluent west German town. Its red-roofed buildings have been restored and the empty spaces left by wartime bombing have been filled with new buildings. However, unlike in many other towns in the former German Democratic Republic, they are actually being used.
The huge former Zeiss plant in the centre of town is now a busy shopping mall. Whereas many east German towns have ageing, shrinking populations, Jena has a young, growing one - so much so that rents are as high as in Berlin. Unemployment stands at 8.6 per cent, which is only slightly higher than the average of 8.2 per cent for the whole of Germany and well below the average of 13.3 per cent for the five states that formed East Germany.
What makes Jena special, says Professor Wilhelm Boland of the Max Planck Institute for Chemical Ecology, is its symbiosis of cutting-edge research and high-end manufacturing. The institute is one of eight research facilities located on the Beutenberg campus, a high-tech industrial park located on a hill on the edge of town where scientists research anything from how light can be used as a scalpel to how microbes communicate. The campus also has two start-up centres that help scientists turn their ideas into profitable businesses.
Although Jena has become something of a model, Prof Boland says its long tradition as what he calls a "knowledge factory" means it will not be easy to quickly replicate its success elsewhere in what used to be the GDR. "This place is in a certain way unique," he explains.