Periodically Poled Lithium Niobate (PPLN)
| Chirped Grating (Mathieu Charbonneau-Lefort) | |
| 160 Gb/s OTDM using a multi-phase optical clock (Jie Huang) | |
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A 4-phase optical clock is generated from a single fs pulse. Each clock phase has a unique color, and is modulated by one of the four WDM channels through DFG process to generate signals at a single wavelength. In this process, each WDM channel is synchronized to one clock phase, and is multiplexed into a TDM signal stream. Link to 2006 SPRC report. |
| Periodically Poled near-stoichiometric Lithium Tantalate (PPSLT) (David Hum) | |
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Wide spread application of periodically poled materials have been limited due to complicated damage mechanisms. These mechanisms intensify as wavelengths become shorter. For visible generation, PPSLT has been shown to
be resistant to these mechanisms. Materials development, and both linear and nonlinear optical characterization are being performed to test the long-term viability of PPSLT for various interactions involving visible wavelengths. Link to 2006 SPRC report. |
| Advanced RPE PPLN Waveguide Applications: Beyond SHG and Uniform QPM Gratings (Carsten Langrock) | |
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We are investigating applications of reverse-proton-exchanged (RPE) periodically-poled lithium niobate (PPLN) waveguide devices for classical and quantum optics applications. These include amplitude control of the quasi-phasematching (QPM) transfer function for short pulse characterization via autocorrelation, frequency resolved optical gating (FROG), and the time-lens method, as well as compact tunable light sources, and continuum generation for optical metrology via carrier envelope phase locking of a mode-locked fiber laser. Furthermore, we will outline the usefulness of previously reported highly-efficient up-conversion devices used for single-photon detection at communication wavelengths for deep-space communication at high bit rates. Link to 2006 SPRC report. |
| Nonlinear optical intergated circuits in congruent and MgO-doped lithium niobate (Rostislav Roussev) | |
| Lithium niobate is a material with large transparency range (350-4500 nm) and large electro-optic coefficient and second-order nonlinear susceptibility. Annealed proton exchange waveguides and reverse proton exchanged waveguides in lithium niobate provide means of increasing nonlinear frequency conversion efficiency by confining the light and helping maintain high intensity over long propagation length. Developing optical integrated circuits using these waveguides allows combining frequency conversion, electro-optic modulation and other functions on a single chip. Recent developments in the modeling of waveguide fabrication and performance allow combining devices on a single chip easier than before. Current focus is on developing modeling for MgO-doped lithium niobate waveguyides which should be resistant to photorefractive damage should allow development of practical devices with extended lifetime operating with visible light. Link to 2006 SPRC report. |
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| Optical Parametric Generation (OPG) in waveguide QPM devices (Xiuping Xie) | |
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Optical parametric generation (OPG) is to amplify the vacuum noise and create coherent light with a strong pump source. The advantage (over OPO, OPA) is its simple setup. The threshold of OPG was reduced to as low as 200pJ per pulse in Reverse-Proton-Exchanged PPLN waveguide devices. By making use of cascaded processes in Multi-Quasi-Phase-Matched grating, it is possible to obtain signals with good temporal properties. By making use of asymmetric Y-junctions, it is possible to generate and separate the signal and idler into different eigenmodes. These progresses enable OPG as an efficient source for quantum communications. The graph (from experiments) shows how the signal pulses grow up and change shape in both frequency domain and time domain when the pump power increases from 0.3nJ to 1.2nJ. The 'new' peak showing up at high pump power comes from the cascaded processes and is near transform-limited. Link to 2006 SPRC report. |
Orientation-Patterned Gallium Arsenide (OP-GaAs)
| Orientation-Patterned Gallium Arsenide: Growth, Characterization, and Applications (Paulina Kuo) | |
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Gallium Arsenide is a very promising material for nonlinear optics because of its large nonlinear coefficient (d14 ~ 94 pm/V at lambda ~ 4um), wide transparency range (0.9-17um) and high thermal conductivity. Because it is optically isotropic, significant nonlinear conversion can only be achieved using quasi-phasematching. An all-epitaxial process has been developed to grow quasi-phasematched GaAs (termed orientation-patterned GaAs or OP-GaAs). Second harmonic and difference frequency generation have been demonstrated in OP-GaAs. More recently, an optical parametric oscillator based on OP-GaAs has been demonstrated with pump between 1.8 and 2 um wavelength and tunable output between 2.28 and 9.14 um. Link to 2006 SPRC report. |
| Tunable Terahertz Generation in Quasi-Phasematched Gallium Arsenide (Joseph E. Schaar) | |
| The capability to quasi-phasematch (QPM) gallium arsenide (GaAs) and its low optical absorption in the terahertz (THz) frequency range make it a promising material for THz generation. We generated 1 mW of average power in a nearly diffraction limited THz wave in room temperature QPM GaAs. The frequency tunable THz wave was created using intra-cavity three-wave mixing of a synchronously-pumped optical parametric oscillator's (SP-OPO) nearly degenerate, orthogonally polarized signal and idler waves. The doubly resonant OPO configuration employed a linear cavity design which avoided back-conversion of the signal and idler in the PPLN. The THz frequency is tunable between 0.65 - 3.4 THz by changing the QPM period of the GaAs or the temperature of the type II periodically-poled lithium niobate (PPLN) crystal. The optical-to-optical conversion efficiency was 0.01 %. Two orders of cascading were observed, as the THz wave mixed with the idler and two red-shifted satellites. Each cascading order transferred energy to a single THz wave as well as the mid-IR satellites. In future work, use of cascading to further increase the THz conversion efficiency will be explored. Link to 2006 SPRC report. |
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LIGO (LASER Interferometer Gravitational Wave Observatory)
| Low dissipation materials and suspensions for interferometric gravitational wave detectors (Sheila Rowan) | |