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Quantum parametric mode sorting has been shown to enable photon counting with precise time gating and exceptional noise rejection that significantly exceeds what is possible with linear filters. While previous experimental demonstrations were in a collinear optical configuration, its response to off-axis scattering must be understood to apply it more broadly in remote sensing missions. To evaluate this prospect, we use a laboratory testbed to examine its performance for detecting photons at small angles, along both forward and backward directions, after passing through strongly scattering media. Our results find no measurable degradation in detecting noncollinear photons along both directions. This finding indicates that the key intra-pulse coherence essential to quantum parametric mode sorting is maintained at a small scattering angle, permitting its applications on a moving platform.

Soliton self-frequency shift (SSFS), a consequence of Raman self-pumping that continuously red-shifts a soliton pulse, has been widely studied recently for applications to fiber-based sources and signal processing. In this paper, the fundamentals of SSFS are reviewed. Various fiber platforms for SSFS (single-mode fiber, microstructured fiber, and higher order mode fiber) are presented and experimental SSFS demonstrations in these fibers are discussed. Observation of Cerenkov radiation in fibers exhibiting SSFS is also presented. A number of interesting applications of SSFS, such as wavelength-agile lasers, analog-to-digital conversion, and slow light, are briefly discussed.

Oceanographic lidar profiles measured in an aerial survey were compared with in situ measurements of water optical properties made from a surface vessel. Experimental data were collected over a two-week period in May 2010 in East Sound, Washington. Measured absorption and backscatter coefficients were used with the volume-scattering function in a quasi-single-scattering model to simulate an idealized lidar return, and this was convolved with the measured instrument response to accurately reproduce the measured temporal behavior. Linear depth-dependent depolarization from the water column and localized depolarization from scattering layers are varied to fine tune the simulated lidar return. Sixty in situ measurements of optical properties were correlated with nearly collocated and coincident lidar profiles; our model yielded good matches (±3 dB to a depth of 12 m) between simulated and measured lidar profiles for both uniform and stratified waters. Measured attenuation was slightly higher (5%) than diffuse attenuation for the copolarized channel and slightly lower (8%) for the cross-polarized channel.

We use the time-lens concept to demonstrate a new scheme for synchronization of two pulsed light sources for biological imaging. An all fiber, 1064 nm time-lens source is synchronized to a picosecond solid-state Ti: Sapphire mode-locked laser by using the mode-locked laser pulses as the clock. We demonstrate the application of this synchronized source for CARS and SRS imaging by imaging mouse tissues. Synchronized two wavelength pulsed source is a major technical difficulty for CARS and SRS imaging. The time-lens source demonstrated here may provide an all-fiber, user friendly alternative for future SRS imaging.

We characterize the focusing properties of the LP02 mode in a typical multiphoton microscope. Under varying back-aperture filling conditions, we measure vastly different point spread functions, including a null at the focus.

We demonstrate an all-fiber, 2-ps, 1063-nm source using time-lens compression of a continuous-wave laser, with variable repetition rates, pulse sequence, and alternating pulse amplitude. We demonstrate Cerenkov radiation in a higher-order-mode fiber using the source.

Using time-lens compression in a loop configuration, we generate 516 fs pulses at 3.5 nJ pulse energy from a continuous-wave 1.55 mum source without mode locking. Just as a spatial lens can expand or focus a beam in space, so can a time-lens broaden or compress a pulse in time. By placing a time-lens in a loop, we maximize the efficiency of bandwidth generation by using one time-lens driven at low power to emulate a stack of many lenses. Our system is compact, is all fiber, and allows large tuning of the repetition rate and continuous tuning of the pulse width and center wavelength.

We generate 516 fs pulses at 3.5 nJ energy from a continuous wave 1.55 mum source without mode-locking. Our system is compact, all-fiber, and allows continuous tuning of pulse width and center wavelength.

We demonstrate a method of generating short pulses at 1350 nm by exciting Cerenkov radiation in a higher-order-mode fiber with a 1064 nm femtosecond fiber laser. We measure a 106 fs, 0.66 nJ output pulse. Cerenkov radiation in fibers allows for energy transfer between a soliton and a dispersive wave, providing an effective and engineerable platform to shift the wavelength of a femtosecond source. With appropriate design of the higher-order-mode fiber, this method of generating short pulses at 1350 nm can be extended to other wavelengths and to higher pulse energies.

We demonstrate soliton self-frequency shift of more than 12% of the optical frequency in a higher-order mode solid, silica-based fiber below 1300nm. This new class of fiber shows great promise for supporting Raman-shifted solitons below 1300nm in intermediate energy regimes of 1 to 10nJ that cannot be reached by index-guided photonic crystal fibers or air-core photonic bandgap fibers. By changing the input pulse energy of 200fs pulses from 1.36 to 1.63nJ we observe Raman-shifted solitons between 1064 and 1200nm with up to 57% power conversion efficiency and compressed output pulse widths less than 50fs. Furthermore, due to the dispersion characteristics of the HOM fiber, we observe redshifted Cerenkov radiation in the normal dispersion regime for appropriately energetic input pulses.

The effect of two-photon absorption on DPSK and OOK transmission is analyzed by simulation. DPSK is found to have an advantage over OOK in both Q and eye closure penalty for multi-channel WDM transmissions.

A dual-polarization lidar and photography are used to sense internal waves in West Sound, Orcas Island, Washington, from a small aircraft. The airborne lidar detected a thin plankton layer at the bottom of the upper layer of the water, and this signal provides the depth of the upper layer, amplitude of the internal waves, and the propagation speed. The lidar is most effective when the polarization filter on the receiver is orthogonal to the transmitted light, but this does not depend significantly on whether the transmitted light is linearly or circularly polarized. The depolarization is greater with circular polarization, and our results are consistent with a single parameter Mueller scattering matrix. Photographs of the surface manifestation of the internal waves clearly show the propagation direction and width of the phase fronts of the internal waves, even though the contrast is low (2%). Combined with the lidar profile, the total energy of the internal wave packet was estimated to be 9 MJ. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). (DOI: 10.1117/1.JRS.6.063611)

We use the time-lens concept to demonstrate a new scheme for synchronization of two pulsed light sources for biological imaging. An all fiber, 1064 nm time-lens source is synchronized to a picosecond solid-state Ti: Sapphire mode-locked laser by using the mode-locked laser pulses as the clock. We demonstrate the application of this synchronized source for CARS and SRS imaging by imaging mouse tissues. Synchronized two wavelength pulsed source is an important technical difficulty for CARS and SRS imaging. The time-lens source demonstrated here may provide an all fiber, user friendly alternative for future SRS imaging.

We demonstrate generation of Cerenkov radiation at 850 nm in a higher-order-mode (HOM) fiber. The LP02 mode in this solid, silica-based fiber has anomalous dispersion from 690 nm to 810 nm. Cerenkov radiation with 3 nJ pulse energy is generated in this module, exhibiting 60% energy conversion efficiency from the input. The HOM fiber provides a valuable fiber platform for nonlinear wavelength conversion with pulse energies in-between index-guided silica-core photonic crystal fibers and air-core photonic bandgap fibers.

We demonstrate tuning of the output spectrum of an HOM fiber module by changing the dispersion curve. Spectral feature wavelengths can be changed systematically by changing the location of the zero-dispersion wavelength.

We demonstrate a method of generating femtosecond pulses at 1350 nm by exciting Cherenkov radiation in a higher-order-mode fiber with a 1064 nm source. We measure a 134 fs, 0.66 nJ output pulse.