Stability of a monolithic integrated filtered-feedback laser.

We experimentally and theoretically investigate the stability of a single-mode integrated filtered-feedback laser as a function of the electrically controlled feedback phase. We interpret the measurements in terms of feedback-induced dynamics, compare them with the results from a stability analysis model for conventional feedback, and find good qualitative agreement.

Sidelobes in the response of arrayed waveguide gratings caused by polarization rotation.

Earlier it was observed that polarization rotation in an AWG built from birefringent waveguides can result in sidelobes in its response. This effect was measured in a polarization sensitive AWG with an orthogonal layout. Now we investigate through detailed simulation whether this effect also exists in polarization desensitised AWGs. It is shown that a dispersion compensated AWG does not suffer from a polarization sidelobe. Alternatively, the AWG can be designed to minimize polarization rotation to suppress the sidelobe.

95 GHz millimeter wave signal generation using an arrayed waveguide grating dual wavelength semiconductor laser.

We report the generation of a 95 GHz carrier frequency by optical heterodyning of two wavelengths from adjacent channels from an arrayed waveguide grating-based multiwavelength laser. The extended cavity structure of the device provides low phase noise and narrow optical linewidth, further enhanced by the intracavity filter effect of the arrayed waveguide grating. We demonstrate that the generated RF beat note, at 95 GHz, has a -3 dB linewidth of 250 kHz. To the best of our knowledge, this is the narrowest RF linewidth generated from a free-running dual-wavelength semiconductor laser. The device is realized as a photonic integrated circuit using active-passive integration technology, and fabricated on a multiproject wafer run, constituting a novel approach for a compact, low-cost dual-wavelength heterodyne source.

A fast low-power optical memory based on coupled micro-ring lasers.

The increasing speed of fibre-optic-based telecommunications has focused attention on high-speed optical processing of digital information. Complex optical processing requires a high-density, high-speed, low-power optical memory that can be integrated with planar semiconductor technology for buffering of decisions and telecommunication data. Recently, ring lasers with extremely small size and low operating power have been made, and we demonstrate here a memory element constructed by interconnecting these microscopic lasers. Our device occupies an area of 18 x 40 microm2 on an InP/InGaAsP photonic integrated circuit, and switches within 20 ps with 5.5 fJ optical switching energy. Simulations show that the element has the potential for much smaller dimensions and switching times. Large numbers of such memory elements can be densely integrated and interconnected on a photonic integrated circuit: fast digital optical information processing systems employing large-scale integration should now be viable.