Donald R. Larson

Integrated-Optic Laser Fabricated by Field-Assisted Ion Exchange in Neodymium Doped Soda-Lime-Silicate Glass

A continuous-wave integrated-optic channel waveguide laser operating at 1.057 microm has been fabricated in neodymium-doped soda-lime-silicate laser glass. The device was end-fire pumped with the 0.528-microm line of an argon-ion laser. Threshold for laser action occurs for an absorbed pump power of 31 mW. The slope efficiency for the integrated-optic laser is estimated to be 0.5%. Field-assisted ion exchange in a eutectic melt of CaNO(3) and KNO(3) was used to form the waveguide.

Y-branch waveguide glass laser and amplifier

A Y-branch channel waveguide laser operating near 1057 nm was fabricated by electric-field-assisted ion exchange in Nd-doped silicate glass. The overall length was 24 mm. Optical pumping was performed with a cw Ti:sapphire laser. Mirrors were bonded to the polished waveguide facets. The slope efficiency was 5.1% when a 4%-transmitting output coupler was used. Threshold was reached at 26-mW absorbed pump power. The device exhibited a single-pass small-signal gain of 0.034 dB/mW when operated as an amplifier. The 3-dB splitting loss of the Y-branch structure was overcome when the absorbed pump power was approximately 85 mW.

Nd:LiTaO 3 waveguide laser

Waveguide lasers operating near 1092 and 1076 nm were fabricated in Z-cut Nd-Ti codiffused LiTaO(3). The Nd diffusion was at 14000 degrees C for 120 h. Samples from two wafers were examined. The Nd film starting thickness was 7 nm in wafer 1 and 15 nm in wafer 2. Ti stripes, 8-15 microm wide, were diffused at 1500 degrees C for 4 h for wafer 1 (130-nm stripe thickness) and 2 h forwafer 2 (100-nm stripe thickness). Pumping was at 750 nm. Threshold occurred at 330 mW of absorbedpump power for the best waveguides from wafer 1 and100 mW for the best waveguides from wafer 2. The slope efficiency of the latter was 0.07%.

Pulse parameter uncertainty analysis

A detailed uncertainty analysis is presented for the pulse parameter measurement service of the National Institute of Standards and Technology (NIST, USA). It relates to the new pulse parameter measurement and extraction processes. Uncertainties for pulse amplitude, transition duration, overshoot and undershoot (preshoot) are given. Effects of temperature variation, impulse response estimate, pulse parameter extraction algorithms, time-base distortion, calibration procedures and the waveform reconstruction process are included.

Extended-cavity operation of rare-earth-doped glass waveguide lasers

Channel waveguides fabricated in Nd-doped glass were used as gain elements for extended-cavity lasers. End-fire pumping was performed with a Ti:sapphire laser operating at 807 nm. The 4-nm FWHM output spectrum was centered near 1057 nm. Slope efficiencies were typically 4-11%, with thresholds near 20 mW. Active mode locking and Q switching were separately performed; mode-locked pulse widths were roughly 80 ps FWHM. Q-switched peak power was 1.2 W. The cw output narrowed to 7 GHz and tuned over a range of 24 nm when a grating provided feedback; single-frequency operation resulted when a high-reflectivity étalon was added.

NIST-NPL interlaboratory pulse measurement comparison

A comparison of the pulse parameter values obtained from the pulse measurement services of the National Institute of Standards and Technology, USA, and the National Physical Laboratory, U.K., was performed. The comparison was based on the pulse parameters of amplitude, transition duration, overshoot, and undershoot (preshoot). The parameter comparison was applied to raw (measured) waveforms, corrected waveforms (if applicable), and reconstructed waveforms. The results of the comparison show that the pulse parameter values for both national laboratories are within published uncertainties.

Waveguide polarizers with hydrogenated amorphous silicon claddings.

We have fabricated TE- and TM-pass waveguide polarizers with polarization isolations of 42 and 35 dB, respectively. The devices were fabricated by the growth of hydrogenated amorphous silicon claddings on K(+)-Na(+) ionexchanged channel waveguides in glass. Cladding thicknesses were accurately tuned to permit optimum coupling of either a TE or a TM mode to the cladding. We have also demonstrated that a waveguide polarizer attenuation as high as 760 dB/cm can be measured by using a photothermal deflection technique.

Sources of uncertainty in the nose-to-nose sampler calibration method

We analyze the nose-to-nose (ntn) method for use as an accurate sampler calibration method. The variations in the measurement of the sampler impulse response using the ntn method are presented, and the validity of the assertion that the kick-out pulse is identical to the sampler impulse response is assessed. Temperature effects on the ntn method are also examined. Finally, the impact of uncertainties in the ntn calibration method on the uncertainties in reported pulse parameters is examined.

Subnanosecond electrical modulation of light with hydrogenated amorphous silicon

A silicon thin‐film interferometer structure is used to demonstrate subnanosecond electrical modulation of light. Both thermally and electrically induced modulations are reported. An electrically induced change in refractive index of 4.7×10−4 is observed.

Reference ballistic chronograph

A ballistic chronograph with an expanded uncertainty of less than ±0.2 m/s has been designed, constructed, and tested. Because of this low uncertainty, this chronograph can be used as a reference to calibrate and/or characterize the performance of commercially available chronographs.