ABSTRACT
CMOS compatible infrared waveguide Si photodiodes are made responsive from 1100 to 1750 nm by Si(+) implantation and annealing. This article compares diodes fabricated using two annealing temperatures, 300 and 475 degrees C. 0.25-mm-long diodes annealed to 300 degrees C have a response to 1539 nm radiation of 0.1 A W-(-1) at a reverse bias of 5 V and 1.2 A W(-1) at 20 V. 3-mm-long diodes processed to 475 degrees C exhibited two states, L1 and L2, with photo responses of 0.3 +/-0.1 A W(-1) at 5 V and 0.7 +/-0.2 A W(-1) at 20 V for the L1 state and 0.5 +/-0.2 A W(-1) at 5 V and 4 to 20 A W(-1)-1 at 20 V for the L2 state. The diodes can be switched between L1 and L2. The bandwidths vary from 10 to 20 GHz. These diodes will generate electrical power from the incident radiation with efficiencies from 4 to 10 %.
ABSTRACT
We describe a self-referenced optical frequency comb generator based on an octave-spanning, prismless Ti:sapphire laser. Dispersion compensation is provided by novel double-chirped mirror pairs and BaF2 wedges. Current versions operate at 80 and 150 MHz. The compact prismless design allows system scaling to a gigahertz repetition rate. Its carrier-envelope beat note is intrinsically stable with a signal-to-noise ratio of 30 dB in a 100-kHz bandwidth. The octave is reached at 25 dB below the average power level. The in-loop accumulated phase error is 1.4 rad (20 mHz to 1 MHz). The technique has the advantages of simplicity and stability compared with previous designs.
ABSTRACT
A balanced cross correlator, the optical equivalent of a balanced microwave phase detector, is demonstrated. Its use in synchronizing an octave-spanning Ti:sapphire laser and a 30-fs Cr:forsterite laser yields 300-attosecond timing jitter measured from 10 mHz to 2.3 MHz. The spectral overlap between the two lasers is strong enough to permit direct detection of the difference in carrier-envelope offset frequency between the two lasers.
