Broadly tunable Tm/Ho-codoped fiber lasers based on temperature-sensitive single-mode-multimode-single-mode fiber structures.

We present all-fiber tunable lasers using single-mode-multimode-single-mode (SMS) structures involving a liquid cladding in the multimode section. We make use of large thermooptic coefficients of the refractive-index liquids to tune the laser oscillation wavelength. The oscillation wavelength is changed over a range of 100 nm from 1858 nm to 1958 nm by controlling the temperature of the SMS structures in the Tm/Ho-codoped fiber ring resonators.

Tunable Tm/Ho-codoped fiber lasers based on an extensible liquid core between a pair of fused multimode-single-mode fibers.

We present mechanically tunable Tm/Ho-codoped fiber lasers based on multimode interference in single mode-multimode-single-mode structures. The intermediate multimode fiber (MMF) is separated into two segments with a liquid core in between. The mode field diameter of the single-mode fiber is designed to 13 µm for the MMF having a core diameter of 105 µm. The tunable range is attained to 64 nm by extending the effective length of the MMF. The laser wavelength is tuned over the ranges of 1809-1866 nm and 1866-1930 nm for the initial MMF lengths of 35.3 and 34.5 mm, respectively.

Magnetic-force-induced long-period fiber gratings.

A novel formation method of a long-period fiber grating (LPFG) based on a magnetic-force-induced microbend is proposed and experimentally demonstrated. The LPFG employs a permanent magnet that exerts transversal force to the fiber by attracting a steel coil spring. The transversal force causes periodic microbending to the fiber, and therefore the transmission wave attenuates at the core-to-cladding mode resonance. This device has advantages of ease of fabrication, reconfigurability, and available for any type of fiber.

All-fiber Q-switched operation of thulium-doped silica fiber laser by piezoelectric microbending.

We demonstrate an all-fiber Q-switched laser operation in the 2 µm region on the basis of a dynamic periodic microbend and pulsed-pump configuration. A single-mode thulium-doped silica fiber is pumped by 1.6 µm-band laser diodes, and the dynamic loss is introduced in the fiber ring resonator by the periodic microbend that is electrically controlled with a piezoelectric actuator. When the voltage-off period of the piezoelectric actuator is set at 20 µs for the pump power of 120 mW, the output pulse power is measured by 420 mW with a pulse width of 1.3 µs.

Tunable Tm-doped fiber ring laser operating at 1.9 µm band using force-induced fiber grating as wavelength tuner.

We report wavelength-tunable operation of a Tm-doped silica fiber laser by using a force-induced long-period fiber grating (LPFG) formed in a fiber ring resonator. The laser output wavelength is tuned by moving the transmission passband that is generated between adjacent resonance wavelengths due to the force-induced LPFG. By changing the grating period around 900 µm, we control the laser output wavelength between 1845 and 1930 nm.

Infectious necrotizing scleritis and proliferative vitreoretinopathy after scleral buckling in a patient with atopic dermatitis.

PURPOSE: To report a case of necrotizing scleritis and proliferative vitreoretinopathy due to an acute infection following scleral buckling for the management of rhegmatogenous retinal detachment in a patient with untreated atopic dermatitis. OBSERVATIONS: A 40-year-old man with untreated atopic dermatitis presented with rhegmatogenous retinal detachment in his right eye. He underwent uncomplicated scleral buckling surgery with an encircling silicon sponge band, then noticed severe hyperemia and purulent discharge in the eye at 3 weeks after surgery. The silicon sponge was exposed and had migrated anteriorly. The patient was then diagnosed with post-scleral-buckling infection and underwent scleral buckle removal. Marked scleral thinning due to necrotizing scleritis was evident beneath the scleral buckle. Eye discharge culture findings were positive for Staphylococcus aureus. After removal of the scleral buckle, the patient's necrotizing scleritis improved, but he developed proliferative vitreoretinopathy. The patient then underwent pars plana vitrectomy, which resulted in reattachment of his retina. CONCLUSIONS AND IMPORTANCE: Although postoperative infection within 1 month after scleral buckling is rare, surgeons should note that patients with atopic dermatitis are at high risk of postoperative infection after scleral buckling, leading to the development of sight-threatening complications such as necrotizing scleritis, which could lead to incomplete retinal attachment and proliferative vitreoretinopathy.

Tunable bandpass filter based on force-induced long-period fiber grating in a double cladding fiber.

We present an all-fiber tunable bandpass filter based on a combination of a force-induced long-period fiber grating and a fiber coil made along a double cladding fiber. The transmission wavelength can be tuned to be in a range of more than 100 nm by changing the grating period mechanically. We can control the transmission amplitude of the bandpass filter by adjusting the periodic force on the double cladding fiber. The ambient temperature causes a positive shift in the transmission wavelength. Such a device is useful for tunable laser applications and fiber-optic sensors.

Type II quasi-phase-matched sum-frequency mixing of diode lasers in KTiOPO4 with broad spectral and temperature acceptance bandwidths.

A 1500-nm-band laser signal is upconverted to the mid-visible part of the spectrum by quasi-phase matched, sum-frequency generation with an 800-nm-band laser pump in a periodically poled KTiOPO4. For an appropriate combination of the two fundamental wavelengths, an acceptance bandwidth of 40-60 nm cm for the pump wavelength is attainable simultaneously with a temperature acceptance bandwidth of 60-70 degrees C cm in an angularly noncritical condition. Using a distributed feedback laser at 1590 nm and a Fabry-Perot laser at 807 nm, we demonstrate a temperature tolerance as large as 60 degrees C with a 10-mm-long crystal.