No abstract

We report operation of a tunable optical parametric oscillator that employs a nonlinear-fiber Sagnac interferometer as a parametric amplifier. The amplifier, which consists primarily of dispersion-shifted fiber that has zero dispersion at 1538 nm, is synchronously pumped with 7.7-ps pulses at 1539 nm. The wide bandwidth of the parametric gain permits tuning of the output signal pulses over a 40-nm range centered on the pump wavelength. The Sagnac interferometer decouples the pump wave from the oscillator cavity while a bandpass filter in the cavity transmits only the signal wave, thereby creating a singly resonant parametric oscillator that is phase insensitive. Whereas we demonstrate tuning over almost the entire bandwidth of Er-doped-fiber amplifiers, one could construct a similar device that operates near the 1310-nm zero-dispersion wavelength of standard telecommunication fiber.

Abstract:$ 4A* 0 .We demonstrate for the first time anti-guided coupling of two adjacent vertical-cavity surface-emitting lasers (VCSEL'S), obtaining a l-by-2 phase-locked array at 869 nm. The lateral index modification required for anti-guiding is achieved by a patterned 3-rim etch performed between two epitaxial growths.In contrast with prior evanescently coupled VCSEL'S, adjacent anti-guided VCSEL'S can emit in-phase and produce a single on-axis lobe in the far field. Greater than 2 mW of in-phase output power is demonstrated with two VCSEL'S separated by 8~m. Moreover, phase locking of two VCSEL'S separated by 20~m is observed, indicating the possibility of a new class of optical circuits based upon VCSEL'S that interact horizontally and emit vertically.

The authors are developing a chip-scale atomic clock (CSAC), more than two orders of magnitude smaller and lower power than any existing technology. As an intermediate milestone, en route to the ultimate CSAC objectives, we have developed a Miniature Atomic Clock (MAC), combining the low-power CSAC physics package with a low-parts count, lowpower digital control and microwave system. The MAC is a complete packaged atomic clock, with overall size of 10 cm 3 , power consumption <200 mW, and short-term stability σ y (τ) ≈ 4x10 -10 τ -1/2 .The MAC provides a valuable testbed for the further development and refinement of the CSAC physics package as well as for the development of the CSAC control electronics prior to undertaking the costly and time-consuming sizereduction effort which will be necessary to meet the ultimate CSAC objectives. The MAC itself may find applications in commercial and military timing systems which require the relatively small size and power consumption of the MAC now, rather than wait for the evolution of the 1 cm 3 , 30 mW CSAC.

A micromachined accelerometer device structure with diffraction-based optical detection and integrated electrostatic actuation is introduced. The sensor consists of a bulk silicon proof mass electrode that moves vertically with respect to a rigid diffraction grating backplate electrode to provide interferometric detection resolution of the proof-mass displacement when illuminated with coherent light. The sensor architecture includes a monolithically integrated electrostatic actuation port that enables the application of precisely controlled broadband forces to the proof mass while the displacement is simultaneously and independently measured optically. This enables several useful features such as dynamic self-characterization and a variety of force-feedback modalities, including alteration of device dynamics in situ. These features are experimentally demonstrated with sensors that have been optoelectronically integrated into sub-cubic-millimeter volumes using an entirely surface-normal, rigid, and robust embodiment incorporating vertical cavity surface emitting lasers and integrated photodetector arrays. In addition to small form factor and high acceleration resolution, the ability to self-characterize and alter device dynamics in situ may be advantageous. This allows periodic calibration and in situ matching of sensor dynamics among an array of accelerometers or seismometers configured in a network.