The end-resonance clock uses strong hyperfine end transition to stabilize the frequency of the local oscillator.
Comparing to the conventional 0-0 atomic clock, end resonance has very small spin-exchange broadening effect. The
spin-exchange rate is proportional to the number density of the alkali-metal atoms. By using the end resonance, we are
able to use very high dense vapor to obtain a much better signal to noise ratio. On the other hand, the end resonance
suffers from the first-order magnetic field dependence. This problem, however, can be solved by simultaneously using a
Zeeman end resonance to stabilize the magnetic field. Here, we report the most recent result of the end-resonance clock.
In addition, we report a whole new technique, push-pull laser-atomic oscillator, which can be thought as all-photonic
clock. This new clock requires no local oscillator. It acts like a photonic version of maser, which spontaneously
generates modulated laser light and modulated voltage signals. The modulation serves as the clock signal, which is
automatically locked to the ground-state hyperfine frequency of alkali-metal atoms.
Low loss, single mode rib waveguides, based on PECVD deposited multi-layer amorphous silicon are fabricated. These waveguide are refractive index and mode-matched to III/V laser waveguides. Methods for monolithic integration of these passive amorphous silicon waveguides with InGaAsP/InP gain sections are demonstrated. Results of a multi-wavelength laser based on an amorphous silicon arrayed waveguide grating integrated on a single chip with InGaAsP gain sections are presented.
Enhanced electrooptic coefficient of GaInAsP three-step quantum wells (3SQW) for high power electrorefraction modulator applications is reported. Measured electrooptic coefficient of the 3SQW is nearly three times higher than the conventional rectangular quantum well (RQW) at lambda=1.55 um. Higher electrooptic effect, combined with a low optical absorption coefficient α<1 cm-1 in the 3SQW increased the modulator figure of merit by nearly 53 times, and decreased the power consumption by nearly one order of magnitude compared with a conventional RQW design.
Low-capacitance, two-section, curved-waveguide gain elements were packaged with lensed polarization-maintaining fiber within standard-sized butterfly-style packages and shown to produce low-jitter pulses when used within a harmonically modelocked sigma cavity laser (jitter = 25 fs; 10 Hz - 10 MHz). Incorporation of a high finesse etalon filter into the sigma-cavity loop resulted in greater than 25 dB suppression of the supermode spurs while maintaining low integrated phase noise (jitter = 30 fs; 10 Hz - 10 MHz). A module containing the in-line sigma-cavity modelocked laser source and packaged semiconductor optical amplifiers was developed to create a configurable low jitter pulse source.