Brian Mathason

Multiwavelength all-optical TDM switching using a semiconductor optical amplifier in a loop mirror

We report simultaneous all-optical switching of multiple wavelengths using an optical loop mirror with an asymmetrically placed semiconductor optical amplifier. Switching is shown for 14-wavelength channels (across 14-nm bandwidth) with switching contrast of 10-23 dB.

All-optical clock recovery using injection mode-locked laser diodes

Semiconductor laser diodes may play an important role in synchronous optical networks as sources of optical modelocked pulse trains with robust timing stability. In this paper, it is demonstrated how injection modelocked semiconductor lasers can be used in all-optical clock recovery systems. Experimental measurement of clock recovery dynamics shows that these devices offer robust clock recovery with low injected data power (less than 6 uW), large repetition rate locking bandwidth (2.9 X 10-3 fractional bandwidth), and small timing jitter (less than 93 fs). Clocking from an injected data stream at 1/50th the clocking repetition rate is demonstrated.

Highly-efficient, high-energy pulse-burst Yb-doped fiber laser with transform limited linewidth

A 1um fiber laser outputting high energy (<1mJ) pulse-bursts with high peak powers (<15kW) and narrow linewidth (<300MHz) is an attractive pump source for tunable periodically poled crystal (PPx) based OPA’s which are used in gas sensing, imaging and communication applications. Here a turn-key 1064nm PM Yb-doped fiber amplifier capable of generating high pulse burst energies with transform limited linewidth is presented. The ~20W average power capable laser is optimized for high energy (0.5-2mJ) and high peak power (<10kW) operation at low duty cycles (<0.1%). The laser is capable of operating at <10x the saturation energy level of the final stage gain fiber and achieves a high level of pulse-to-pulse peak power uniformity within pulse-burst. Stimulated Brillion Scattering (SBS) limited micro pulse energy up to 40uJ is achieved and SBS dependence on micro pulse width and separation are characterized. High wall plug efficiency (<20%) for the FPGA controlled system is maintained by temporal and spectral ASE suppression and by spreading the necessary pulse pre-shaping losses (~12dB) to three different amplitude modulation points in the amplifier chain.

Simultaneous multiwavelength switching for parallel information processing

Parallel transmission and processing of high-speed data may be accomplished by using multiple wavelength channels. To process this type of wavelength division multiplexed information, it is necessary to be able to switch the multiple wavelengths, simultaneously. In this paper we demonstrate multiwavelength switching with a single switch, utilizing a nonlinear optical loop mirror with a semiconductor optical amplifier. Switching is shown for 14 wavelength channels across a 14-nm bandwidth for data rates up to 2.5 GHz. Switching contrasts of 10 dB are shown with control energy as low as 1.6 pJ.

Recent advances in high-power ultrafast mode-locked laser diodes

Semiconductor diode lasers are playing important roles in high speed information processing, telecommunications, and high speed measurement and diagnostic systems. This paper presents recent developments in the generation, amplification, and utilization of high power modelocked optical pulses from traveling wave semiconductor optical amplifier devices.

High Energy, Narrow Linewidth 1572nm Eryb-Fiber Based MOPA for a Multi-Aperture CO2 Trace-Gas Laser Space Transmitter

A cladding-pumped, LMA ErYb fiber-based, amplifier is presented for use in a LIDAR transmitter for remote sensing of atmospheric CO2 from space. The amplifier is optimized for high peak power, high efficiency, and narrow linewidth operation at 1572.3nm. Using highly reliable COTS components, the amplifier achieves 0.5kW peak power (440uJ pulse energy), 3.3W average power with transform limited (TL) linewidth and M2<1.3. The power amplifier supports a 30% increase in pulse energy when linewidth is increased to 100MHz. A preliminary conductively cooled laser optical module (LOM) concept has size 9x10x1.25 in (113 in3) and estimated weight of 7.2lb (3.2 kg). Energy scaling with pulse width up to 645uJ, 1.5usec is demonstrated. A novel doubleclad ErYb LMA fiber (30/250um) with high pump absorption (6 dB/m at 915nm) was designed, fabricated, and characterized for power scaling. The upgraded power amplifier achieves 0.8kW peak power (720uJ pulse energy) 5.4W average power with TL linewidth and M2<1.5.

Experiment and simulations of lock-up time and dephasing time for all-optical clock recovery with a mode-locked semiconductor laser system

Summary form only given. Recently, mode-locked semiconductor lasers have been shown to exhibit robust synchronization dynamics, making them well suited for clock recovery applications. Two important properties of a clock recovery oscillator are a short lock-up time (to reduce system latency) and a long dephasing time (to avoid clock disruption). We present results of experimental measurements and simulation of clock lock-up and dephasing time for an optical clock recovery oscillator.

All-optical multiwavelength switching for hybrid WDM/TDM demultiplexing and signal processing

Summary form only given. Hybrid approaches to optical communications and signal processing systems have previously been proposed that exploit the parallelism of wavelength division multiplexing (WDM) and the speed of time division multiplexing (TDM). In this paper, we demonstrate an all-optical switch capable of simultaneously switching multiple wavelength channels with high-speed capability using a semiconductor optical amplifier (SOA) asymmetrically placed inside a loop mirror.

Efficient, space-based, PM 100W thulium fiber laser for pumping Q-switched 2um Ho:YLF for global winds and carbon dioxide lidar

Global wind measurements are critically needed to improve and extend NOAA weather forecasting that impacts U.S. economic activity such as agriculture crop production, as well as hurricane forecasting, flooding, and FEMA disaster planning.1 NASA and the 2007 National Research Council (NRC) Earth Science Decadal Study have also identified global wind measurements as critical for global change research. NASA has conducted aircraft-based wind lidar measurements using 2 um Ho:YLF lasers, which has shown that robust wind measurements can be made. Fibertek designed and demonstrated a high-efficiency, 100 W average power continuous wave (CW) 1940 nm thulium (Tm)- doped fiber laser bread-board system meeting all requirements for a NASA Earth Science spaceflight 2 μm Ho:YLF pump laser. Our preliminary design shows that it is possible to package the laser for high-reliability spaceflight operation in an ultra-compact ~ 2″x8″x14″ size and weight <8.5 lbs. A spaceflight 100 W polarization maintaining (PM) Tm laser provides a path to space for a pulsed, Q-switched 2 μm Ho:YLF laser with ~ 30-80 mJ/pulse range at 100-200 Hz repletion rates.

Fiber-based, trace-gas, laser transmitter technology development for space

NASA’s Goddard Space Flight Center (GSFC) is working on maturing the technology readiness of a laser transmitter designed for use in atmospheric CO2 remote-sensing. GSFC has been developing an airplane-based CO2 lidar instrument over several years to demonstrate the efficacy of the instrumentation and measurement technique and to link the science models to the instrument performance. The ultimate goal is to make space-based satellite measurements with global coverage. In order to accomplish this, we must demonstrate the technology readiness and performance of the components as well as demonstrate the required power-scaling to make the link with the required signal-to-noise-ratio (SNR). To date, all the instrument components have been shown to have the required performance with the exception of the laser transmitter. In this program we are working on a fiber-based master oscillator power amplifier (MOPA) laser transmitter architecture where we will develop a ruggedized package and perform the relevant environmental tests to demonstrate TRL-6. In this paper we will review our transmitter architecture and progress on the performance and packaging of the laser transmitter.