Eric D. Park

Multiwavelength mode-locked InGaAsP laser operating at 12 ch/spl times/2 GHz and 16 ch/spl times/10 GHz

In this letter, we report on the development and characterization of an InGaAsP semiconductor optical amplifier-(SOA) based ring cavity laser that emits up to 16 wavelengths in the 1550-nm region. The laser is loss modulation mode locked at up to 10 GHz with temporal pulses of /spl sim/25 ps. Spectral control of the emission is accomplished by an intracavity 4-f spectral pulse shaper with a programmable liquid crystal spatial light modulator (SLM) in the Fourier plane. Voltage control of the transmissibility of the pixels of the SLM defines the wavelength channels and allows flattening of channels to produce a uniform intensity of channel outputs.

Multiwavelength generation at 1.55 μm from an external cavity semiconductor laser

Optical analog to digital conversion schemes require a sampling source of high repetition rate, low temporal jitter, low amplitude noise, and short pulse duration to achieve the desired sampling rate and number of bits of resolution. We report on the development of an actively mode-locked semiconductor external cavity laser system where the emission is comprised of multiple wavelengths nominally centered around 1.55 microns. Cavity design includes an intra-cavity grating to produce a spatially dispersed optical spectral filtering plane. Amplitude filtering in this spectral plane serves to flatten the effective gain and a rectangular aperture array selects those wavelengths which are allowed to lase. Modelocked at 311 MHz and producing 8 spectral lines, the laser provides a sampling rate of approximately 2.5 GHz. Temporal interleaving of the pulse train by factor 4 increases the sampling rate to 10 GHz.

16/spl times/10 GHz multiwavelength mode locked InGaAsP laser with closed loop spectral control

Summary from only given. We report on the design and development of a semiconductor optical amplifier based multiwavelength laser. This work expands upon previous efforts utilizing external cavity oscillators based on SOAs at both 830 and 1550 nm. The laser configuration is shown as a unidirectional ring cavity that comprised of 2.3 mm MQW InGaAsP SOA bulk optics.

Ultra-compact solid state laser

We have built a small passively Q-switched solid-state laser with a volume of < 8 cm3 and a weight of < 20 g. The laser is passively Q-switched using a Cr4+ :YAG saturable absorber to generate pulses < 2 ns. The architecture is applied to different laser crystals such as Nd:YLF and Nd:YVO4 that produced 2 mJ at 20 Hz and 0.3 mJ at 10 kHz, respectively. The laser is side-pumped by single or stacked diode bars using a unique pump cavity to homogenize the pump intensity in the laser rod as well as make the structure alignment insensitive when subjected to shock, vibration, and thermal cycling. The laser components can easily be modified to change the output wavelength to green, UV, or mid IR.

All-fiber widely tunable 2 μm fiber laser

We report on the development of an all-fiber, 793-nm cladding-pumped tunable Tm-doped fiber laser based on a voltage driven 2-μm, intra-cavity, fiber-coupled, Fabry-Perot tunable filter. Continuous tuning over a 90-nm range has been achieved from 1952 to 2042 nm with a spectral linewidth ≤0.07 nm and an optical signal-to-noise ratio <55 dB. A wavelength stability of ±0.01 nm over a run time of 2 hours has been demonstrated. The desired wavelength from the available 90 nm of tuning range can be selected by the filter with a kHz repetition rate.

Mode-locked tunable thulium-doped fiber laser

We report on an all-fiber, actively mode-locked, tunable, Thulium-doped, fiber laser based on a 20-GHz bandwidth electro-optic intensity modulator (EOM) and a voltage driven 2-μm, intra-cavity, fiber-coupled, Fabry-Perot tunable filter (FFP-TF). The repetition rate of output pulses was 47 MHz and the shortest measured output pulse width was 445 ps. A continuous tuning range of 88 nm has been achieved from 1954 to 2042 nm with a spectral linewidth ≤0.14 nm and an optical signal-to-noise ratio <55 dB. The fiber laser offers an amplitude stability of ±0.2 dB and a wavelength stability of ±0.02 nm over 2 hours.

A compact solid state laser

A compact laser producing green wavelength with a volume of <; 8 cm3 and a weight of < 80 g finds its application in many fields from military to space based. We built a small solid-state laser that produces 1 mJ of energy per-pulse at a 1 - 20 Hz repetition rate. The laser is passively Q-switched using a Cr4+:YAG saturable absorber to generate pulses <10 ns. A nonlinear crystal doubles the frequency to generate light at 523 nm. The laser is side-pumped by a single bar diode laser using a unique pump cavity to homogenize the pump intensity in the laser rod. The laser components can easily be modified to change the output wavelength from UV to mid IR.

Compact, passively q-switched 523-nm laser

A compact laser with a volume of < 8 cm3 and a weight of < 80 g finds its application in many fields from military to space based. We built a small solid-state laser that produces 1 mJ of energy per-pulse at a 1 - 20 Hz repetition rate. The laser is passively Q-switched using a Cr4+:YAG saturable absorber to generate pulses < 10 ns. A nonlinear crystal doubles the frequency to generate light at 523 nm. The laser is side-pumped by a single bar diode laser using a unique pump cavity to homogenize the pump intensity in the laser rod. The laser components can easily be modified to change the output wavelength from UV to mid IR.

Dependence of ultra-low timing jitter on intra-cavity loss for modelocked semiconductor light sources

Summary form only given. The use of stable optical pulse-trains as sampling pulses may allow for accurate analog-to-digital conversion of wide-band RF signals. Specifically, 10 Gbps pulse trains with 10 fs of timing jitter could provide for 12-bit A/D conversion of 10 GHz signals. Modelocked semiconductor lasers may provide the needed sampling pulses for such an application. In determining timing jitter, the phase noise is typically integrated at offset frequencies below 10 MHz. To be useful for such systems, however, characterization of the phase noise up to the roundtrip frequency may be needed. In the paper, comparative measurements of timing jitter (10 Hz to 10 MHz) of a modelocked semiconductor laser under gain and loss modulation is shown. Further, a numerical model incorporating spontaneous emission is developed which points toward low-frequency noise as the main source of jitter. Indications of total timing jitter (10 Hz-5 GHz) of the order of 40 fs is given.

Frequency-tunable UV laser system for biological and chemical detection

An efficient, compact, tunable ultraviolet laser system has been constructed by frequency tripling a Q-switched, tunable near-infrared Cr:LiSAF laser source. The nonlinear conversion from the fundamental to the third harmonic was accomplished through second harmonic generation in lithium triborate (LBO) followed by sum frequency mixing of the fundamental and the second harmonic in beta-barium borate (BBO). Third harmonic output with this combination of nonlinear crystals has yielded 5 mJ of energy at 280 nm with an overall conversion efficiency of 7%. The Cr:LiSAF master oscillator has been modeled in detail to optimize performance. System specifications of tuning range, linewidth, output energy, temporal behavior, and repetition rate were determined by the end use application as a UV excitation source for a chemical and biological stand-off detection system.