Christine Spiegelberg

Low-noise narrow-linewidth fiber laser at 1550 nm (June 2003)

We present a compact integrated fiber laser with more than 200 mW of output power. It combines polarized fiber output with very narrow linewidth of less than 2 kHz. The coherence length of the laser is measured to be longer than 5 km. The laser features high mode stability of less than /spl plusmn/10 MHz over hours. The relative intensity noise (RIN) spectrum is dominated by a peak at the relaxation oscillation frequency and is shot-noise limited otherwise. The RIN peak at 1 MHz is reduced to /spl sim/-130 dB/Hz by integrating a negative feedback circuit. In addition to thermal wavelength tuning, the laser frequency can be modulated at a bandwidth of up to 10 kHz via the piezoelectric effect.

Narrow linewidth fiber laser for 100-km optical frequency domain reflectometry

A diode-pumped single-frequency piezoelectrically tuned fiber laser with narrow spectral linewidth has been used as a light source in applications for long-range coherent frequency-domain reflectometry. Frequency-modulated continuous-wave (FMCW) measurements of Rayleigh back-scattering and Fresnel reflection from a 95-km-long fiber have been demonstrated without the use of an optical amplifier. This is, to our knowledge, the longest distance measurement with FMCW. The high sensitivity and dynamic range of the long-range backscattering measurements benefit from the extremely long coherence length of the narrow linewidth fiber laser, which has been estimated to be 210 km in air.

Single-frequency, all-fiber Q-switched laser at 1550-nm

We present a novel actively Q-switched single frequency, linear, all-fiber laser using fast stress-induced birefringence modulation. We demonstrate 25-W peak power in 12-ns, 0.3-µJ pulses at a repetition rate of 80 kHz with 370 mW of pump power, without using an amplifier. Very effective Q-switching was also observed at 325 kHz, near the resonance frequency of the piezoelectric actuator. Using a higher pump power of 780 mW, an average output power of 85 mW and pulsewidth of 16 ns at 325 kHz PRF was observed.

Light amplification and laser emission in conjugated polymers

Seppo Honkanen, MEMBER SPIE Mahmoud Fallahi, MEMBER SPIE Bernard Kippelen Nasser Peyghambarian, MEMBER SPIE University of Arizona Optical Sciences Center Tucson, Arizona 85721 Abstract. We study optical gain and laser emission from semiconducting conjugated polymers after strong optical excitation with femtosecond laser pulses. Stimulated emission from few-hundred-nanometer thin films results in a sharp increase in emission intensity and emission line narrowing. Very large optical gain due to the stimulated emission is measured directly by pump-probe spectroscopy. Using the large light amplification in these conjugated polymers, we demonstrated planar and ring lasers of very small sizes that are suitable for applications in integrated optics. Vertical cavity surface emitting lasers, distributed feedback through surface relief grating, and whispering-gallery mode emission from ring resonators are demonstrated.

Efficient coherent beam combining of fiber lasers using multiplexed volume Bragg gratings

Highly efficient, stable, and scalable passive coherent beam combining of fiber lasers using multiplexed volume Bragg gratings is presented. We report combining efficiency of >;90% for two channels and demonstrate channel scalability to four channels.

Multiplexed Reflective Volume Bragg Grating for Passive Coherent Beam Combining

Multiplexed Bragg grating recorded in photo-thermo-refractive glass can be efficient combiner for coherent locking of high-power lasers. Spectral properties of two-channel combiner are studied theoretically and experimentally. Multi-channel scaling of this approach is discussed.

Cladding-pumped distributed feedback phosphate glass fiber lasers

Distributed feedback (DFB) phosphate glass fiber lasers that are cladding pumped with multimode diodes have been demonstrated. Single and cascaded DFB lasers with outputs up to 160 mW and 1 W, respectively, have been achieved.

Microstructured and multicore fibers and fiber lasers

Microstructured and multi-core fiber lasers were fabricated that have produced more than 1.3 W/cm at 1.5 mum. Near 2 W single frequency, single-transverse-mode output was demonstrated

A compact 100-km FMCW fiber laser radar

Frequency-modulated continuous wave (FMCW) measurements of Rayleigh back-scattering and Fresnel reflection from 95-km fiber have been demonstrated with a compact piezo-electrically-tuned sub-kilohertz-linewidth fiber laser. This is, to our knowledge, the longest distance measurement with FMCW.

Characterization of coherence properties of a free-running sub-kilohertz-linewidth fiber laser by FMCW

Frequency-modulated continuous wave (FMCW) measurements of Rayleigh backscattering in 85-km fiber derives coherence length of a free-running sub-kilohertz-linewidth fiber laser to be 210 km and the longest distance is measured with FMCW.