Martin Hempstead

Efficient and compact green laser for micro-projector applications

— Efficient and compact green lasers are keystone components for micro-projector applications in mobile devices. An architecture that consists of an infrared-producing DBR (distributed Bragg reflector) laser with a frequency-doubling crystal is used to synthesize a green laser that has high electrical-to-optical conversion efficiency and can be modulated at speeds required for scanner-based projectors. The design and performance of a green-laser package that uses adaptive optics to overcome the challenge of maintaining alignment between the waveguides of the DBR laser and the frequency-doubling crystal over temperature and lifetime is described. The adaptive optics technology that is employed uses the piezo-based smooth impact drive mechanism (SIDM) actuators that offer a very small step size and a range of travel adequate for the alignment operation. The laser is shown to be compact (0.7 cm3 in volume) and capable of a wall-plug efficiency approaching 10% (at 100-mW green power). It was demonstrated that the adaptive optics enables operation over a wide temperature range (10–60°C) and provides the capability for low-cost assembly of the device.

Compact and efficient green lasers for mobile projector applications

— Efficient and very-compact projectors embedded into mobile consumer-electronic devices, such as handsets, media players, gaming consoles, and GPS units, will enable new consumer use and industry business models. A keystone component for such projectors is a green laser that is commensurately efficient and compact. A synthetic green-laser architecture is described that can achieve efficiencies of 15%. The architecture consists of an infrared distributed Bragg reflector laser coupled into a second-harmonic-generation device for conversion to green.

Time-resolved performance analysis of a second-order PMD compensator

Design, test, and performance requirement and analysis for a polarization-mode-dispersion compensator (PMDC) with four degrees of freedom is presented. The performance is analyzed on the basis of time-integrated and time-resolved bit-error ratio (BER) measurements. Signal impairments are generated by both, first- and higher-order emulators. The probability distributions of bit errors measured over many one second intervals exhibit very long tails. Therefore even a PMDC with a good average BER performance may result in a significant total outage time for a given system.