Semi-guiding high-aspect-ratio core (SHARC) fiber amplifiers with ultra-large core area for single-mode kW operation in a compact coilable package.

A new class of optical fiber, the SHARC fiber, is analyzed in a high-power fiber amplifier geometry using the gain-filtering properties of confined-gain dopants. The high-aspect-ratio (~30:1) rectangular core allows mode-area scaling well beyond 10,000 μm2, which is critical to high-pulse-energy or narrow-linewidth high-power fiber amplifiers. While SHARC fibers offer modally dependent edge loss at the wide "semi-guiding" edge of the waveguide, the inclusion of gain filtering adds further modal discrimination arising from the variation of the spatial overlap of the gain with the various modes.

Er-doped high-aspect-ratio core rectangular fiber producing 5 mJ, 13 ns pulses at 1572 nm.

We have produced 5 mJ, 13 ns pulses using a very large-mode-area rectangular fiber containing a high-aspect-ratio core with dimensions of ~30 μm×580 μm. The rectangular fiber design retains a thin cladding dimension ~0.5 mm, which is compatible with a compact coiled package.

Semi-guiding high-aspect-ratio core (SHARC) fiber providing single-mode operation and an ultra-large core area in a compact coilable package.

A new class of optical fiber is presented that departs from the circular-core symmetry common to conventional fibers. By using a high-aspect-ratio (~30:1) rectangular core, the mode area can be significantly expanded well beyond 10,000 μm2. Moreover, by also specifying a very small refractive-index step at the narrow core edges, the core becomes "semi-guiding," i.

Near-diffraction-limited operation of step-index large-mode-area fiber lasers via gain filtering.

We present, for the first time to our knowledge, an explicit experimental comparison of beam quality in conventional and confined-gain multimode fiber lasers. In the conventional fiber laser, beam quality degrades with increasing output power. In the confined-gain fiber laser, the beam quality is good and does not degrade with output power.

Correction of phase and depolarization distortions in a multimode fiber at 1.064 microm with stimulated-Brillouin-scattering phase conjugation.

We have used phase conjugation to compensate phase distortions and depolarization introduced in multimode fibers having 2-m lengths and 400-microm core diameters. The experiment was performed at a wavelength of 1.064 microm, and we achieved phase conjugation using Brillouin-enhanced four-wave mixing in a 0.

Single-frequency, 500-ns laser pulses generated by a passively Q-switched Nd laser.

We demonstrate a simple, passive technique for producing 500-ns pulse lengths with a Nd laser. The measured 1.5-MHz upper limit to the pulse spectral width indicates that it is nearly transform limited.

The cost of accreditation: one hospital's experience.

Objective: The 1989 survey conducted by the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) at the UCLA Neuropsychiatric Hospital was the hospital's first using standards outlined in the 1989 edition of JCAHO's Accreditation Manual for Hospitals. The authors' goal was to calculate the cost of preparing for and undergoing the 1989 survey.

Methods: Costs associated with planning for the survey and conducting a mock survey and the actual survey were based on records of staff time spent on those activities, fees for consultant services, and fees for the actual survey.

Stimulated Brillouin scattering phase-conjugation fidelity fluctuations.

We observe shot-to-shot fluctuations in the far-field fidelity of stimulated Brillouin scattering phase-conjugate mirrors in the saturated reflectivity regime under various experimental conditions. The fluctuations, which are not seen in the reflectivity, reflect a partial breakdown in the discrimination mechanism that selectively amplifies the conjugate mode above the stimulated Brillouin scattering noise seed.

The emotional impact of surgery and the value of informed consent.

The process of obtaining consent detailed here contains within it most of the therapeutic techniques useful in the prevention and treatment of usual postoperative psychological complications. You will note that at various points the physician will have; given information, utilized suggestions, reflected feelings, allowed ventilation and catharsis, clarified, desensitized, increased self-esteem, given reassurance, fostered identification, supported healthy defenses, encouraged autonomy, control, and responsibility, and done some social engineering. These psychotherapeutic techniques have been built into the content and process of eliciting consent.

Tennis injuries: prevention and treatment. A review.

When players are engaged in the sport of tennis, injuries may occur to the eyes, in the neck, to the shoulder and back, arm and elbow, wrist and hand, and feet. The key to prevention and treatment of these injuries is good coaching and a formal stretching and strengthening program. The drooped "tennis shoulder" of professionals and senior tennis players is a natural response to heavy use.

The Long-Term Effects of Playing Tennis.

In 50 years of competitive tennis these super seniors have stayed in good condition and overcome problems ranging from tennis shoulder to heart disease.

The tired patient.

One of the most challenging diagnostic problems that comes into the physician's office is the patient who complains of "being tired." It can prove to be a frustrating experience for the physician (especially if the physician is also tired) and to the patient. This article will propose and describe a two-pronged systematic approach to the patient that can increase the probability of a satisfying outcome for both physician and patient.

Psychologic and psychophysiologic response to 105 days of social isolation.

The responses of nine subjects to 105 d of social isolation are reported. The study reveals that crew selection plus ongoing support by psychiatric staff permits continued function in an exotic milieu. Prediction of psychophysiologic symptoms was possible using paper and pencil tests.