Center Valley, PA, United States
Center Valley, PA, United States

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Zhao P.,Lehigh University | Ragam S.,Lehigh University | Ding Y.J.,Lehigh University | Zotova I.B.,ArkLight, Inc
Optics Letters | Year: 2010

We have demonstrated a compact and portable terahertz (THz) source, based on difference-frequency generation in a GaSe crystal. The two input frequencies, required for achieving frequency mixing, are generated by a single Qswitched Nd:YLF laser incorporating two laser resonators. The average power of the THz output reaches 1 ìW at 1:64 THz (182 ìm) within a linewidth of 65 GHz. Such a THz source can be packaged into a compact and portable system. © 2010 Optical Society of America.


Li D.,Lehigh University | Jiang Y.,Lehigh University | Ding Y.J.,Lehigh University | Zotova I.B.,ArkLight, Inc | Prasad N.S.,NASA
Applied Physics Letters | Year: 2012

We have implemented a single-photon detection system in the 1.55-μm region, based on frequency up-conversion in MgO-doped periodically poled LiNbO 3 waveguide. We have subsequently reached a record-low dark count rate of 45 counts per second. The detectable signal photon rate, i.e., the rate for counting the up-converted photons corrected by the dark counts, noises, and losses, reaches a record-low value of 81 photons per second. Through free-space coupling, we have eliminated the dark counts induced by parametric fluorescence. © 2012 American Institute of Physics.


Zhao P.,Lehigh University | Ragam S.,Lehigh University | Ding Y.J.,Lehigh University | Zotova I.B.,ArkLight, Inc
Applied Physics Letters | Year: 2012

We demonstrate intracavity terahertz generation from an output coupler of a compact dual-frequency solid state laser. The output coupler consisting of unbonded and stacked GaP plates is used as a second-order nonlinear medium where the difference-frequency generation takes place. When quasi-phase matching is achieved within the alternatively rotated GaP plates, terahertz output power is significantly enhanced compared with that for the corresponding external-cavity configuration. © 2012 American Institute of Physics.


Zhao P.,Lehigh University | Ragam S.,Lehigh University | Ding Y.J.,Lehigh University | Zotova I.B.,ArkLight, Inc
Optics Letters | Year: 2011

When two Nd:YLF crystals share a Cr:YAG crystal functioning as a single passive Q switch, the timing jitter between each pair of dual-frequency pulses generated by the two crystals has been reduced by a factor of 20. Such a reduction in the timing jitter allows us to generate terahertz pulses by focusing such a passively Q-switched laser beam onto a nonlinear crystal. Such a result represents the first step for us to eventually implement a compact terahertz source based on ultracompact microchip lasers. © 2011 Optical Society of America.


Jiang Y.,Lehigh University | Li D.,Lehigh University | Ding Y.J.,Lehigh University | Zotova I.B.,ArkLight, Inc
Optics Letters | Year: 2011

By stacking alternatively rotated gallium phosphide (GaP) plates, the maximum photon conversion efficiency of 40% for the terahertz (THz) generation based on difference-frequency generation has been achieved. The corresponding peak power generated inside the four GaP plates approaches 4kW. As the number of plates is increased from four to five, the THz output power is significantly decreased, due to back parametric conversion. © 2011 Optical Society of America.


Zhao P.,Lehigh University | Ragam S.,Lehigh University | Ding Y.J.,Lehigh University | Zotova I.B.,ArkLight, Inc
Applied Physics Letters | Year: 2011

We investigate power scalability and frequency agility of a terahertz (THz) source by mixing two frequencies generated by solid-state lasers in a nonlinear crystal. They are made possible by introducing two solid-state laser crystals sharing the same Q switch and output coupler with the same laser beams decoupled to each other by a polarizer. Following the optimization, we have improved the THz output power nearly fivefold at 1.64 THz. By replacing one of the neodymium-doped lithium yttrium fluoride crystals with a neodymium-doped yttrium aluminum garnet crystal, we have produced 2.1 μW at 2.98 THz. © 2011 American Institute of Physics.


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 600.00K | Year: 2011

PI at ArkLight proposes to implement photon counting detectors at near-IR (1-1.8 microns) and mid-IR (3-4 microns) with single photon sensitivity based on frequency up-conversion during Phase 2, representing an innovative Lidar technology for ASCENDS mission. By working with Prof. Ding at Lehigh University, PI will explore fundamental limits to quantum efficiencies for up-conversion detection at 1.57 microns. She will implement, characterize, and optimize single up-conversion device capable of detecting 1.57 microns and 1.27 microns. She plans to achieve detections of CO2 and O2 using implemented up-conversion device. She will investigate fundamental limits to noises for up-conversion detections. She will compare among PPLN, PPKTP, and PPLT as up-conversion media. She will expand detection wavelengths to cover ranges of 1-1.8 microns and 3-4 microns. She plans to introduce novel techniques for improving performances of up-conversion devices. She will investigate versatility of up-conversion devices under harsh environments. To achieve all these objectives, she has laid out a detailed work plan describing all the specific tasks necessary. Through optimizations, she will achieve the quantum efficiency of 50%, dark count rate of 50 Hz, bandwidth of GHz, electrical consumption of<1 W, weight of<1 lb, and dimension of 7x4x4 (all in inches).


Grant
Agency: Department of Defense | Branch: Army | Program: SBIR | Phase: Phase I | Award Amount: 70.00K | Year: 2011

By closely working with Prof. Ding"s group at Lehigh University, PI proposes to take a revolutionary approach to THz generation based on difference-frequency generation. Such a nonlinear process will take place inside the cavity of a dual-wavelength Yb:YAG laser. PI plans to demonstrate dual-wavelength operation of CW and Q-switched Yb:YAG lasers. PI"s goal is to reach the output powers of at least 1 W at each of the dual wavelengths. Subsequently, PI will achieve efficient conversion between the optical waves generated by the dual-wavelength laser and a THz output outside a Q-switched Yb:YAG laser cavity. The highest output power is expected to be 200 nW at 1 THz. PI is going to carry out feasibility studies on intracavity THz generation based on the performances of the CW and Q-switched Yb:YAG lasers tested and THz generation achieved outside the laser cavity. According to PI"s estimate, it is feasible for her to improve the THz output power to 1 mW. Moreover, she will be able to achieve the tuning range of 150 GHz - 1 THz, the linewidth of 100 MHz, and the repetition rate of 10 kHz. PI will also develop a concrete plan for identification and detection of biological agents.


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 100.00K | Year: 2010

PI at ArkLight proposes a novel approach to photon counting detectors at near-IR (1-1.8 µm) and mid-IR (3-4 µm) with single photon sensitivity, representing an innovative Lidar technology for ASCENDS mission. She will convert the input signals at 1.27 µm and 1.57 µm to those at 579 nm and 634 nm, respectively, within a periodically-poled LiNbO3 wafer, pumped by a Nd:YAG laser at 1.064 µm or a 200-mW InGaAs laser at 980 nm. The anticipated results for Phase 1 include demonstrations of efficient frequency up-conversion from 1.27 µm and 1.57 µm to 579 nm and 634 nm, determination of fundamental limits to noise equivalent powers, performance of the proposed detection system after optimizations, a final design of an ultra-compact detection system after considering e.g. an intracavity configuration, and reports. Beginning/end (Phase 1): TRL 1/3. The anticipated results for Phase 2 include implementation and testing of the ultra-compact detection system, measurement and analysis of noise equivalent powers and photon sensitivities, expansion of detection wavelengths to 1-1.8 µm and 3-4 µm, feasibility analysis of single-photon sensitivity, design, implementation, and testing of a battery-powered, cell-phone-sized, and integrable detection system with single photon sensitivity being achieved, to be tested in space-based platforms, and reports.


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 100.00K | Year: 2011

PI at ArkLight proposes a novel scheme for making cloud discrimination in the wavelength ranges of near-IR (1-1.8µm) and mid-IR (3-4 µm). This scheme is based on optical phase conjugation from a second-order nonlinear medium. It overcomes the disadvantages of slow speed in photorefractive media and poor reflectivities in third-order nonlinear materials. During Phase 1, she will design novel phase-conjugate mirrors operating at the signal wavelengths of 1.27 µm and 1.57 µm. Subsequently, she will fabricate the designed phase-conjugate devices. The next step will be testing of the fabricated devices by investigating sum-frequency and difference-frequency generation in the transverse geometry. She will also carry out modeling efforts on the device performances for making cloud discrimination. This Phase 1 project will be carried out in collaboration with Prof. Ding at Lehigh University who is one of the pioneers in optical phase conjugation. The anticipated results for Phase 2 include implementation and testing of the phase-conjugate mirrors operating at 1.27 µm and 1.57 µm for correcting phase distortion and making cloud discrimination, optimization of the phase-conjugate mirrors, finding solutions to practical issues for deploying these mirrors in the ASCENDS mission, expansion of input wavelengths, incorporation with frequency up-conversion devices, and reports.

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