T. Erdogan

Decay of ultraviolet‐induced fiber Bragg gratings

We report measurements of thermally induced decay of fiber Bragg gratings patterned by ultraviolet irradiation in germanium‐doped silica fiber. The decay is well characterized by a ‘‘power‐law’’ function of time with a small exponent, which is consistent with the rapid initial decay followed by a substantially decreasing rate of decay. We propose a decay mechanism in which carriers excited during writing are trapped in a broad distribution of trap states, and the rate of thermal depopulation is an activated function of the trap depth. This model is consistent with the observed power‐law behavior. An important consequence of this mechanism is that the decay of the induced index change can be accelerated by increasing temperature. A decelerated‐aging experiment verifies this prediction. This result demonstrates that it is possible to preanneal a device incorporating ultraviolet‐induced refractive‐index changes, wiping out the portion of the index change that would decay over the lifetime of the device, and ...

Ultraviolet laser fabrication of ultrastrong optical fiber gratings and of germania-doped channel waveguides

We report the fabrication of low loss (<0.2 dB) fiber Bragg gratings of 10 nm reflection bandwidth, and of 19 nm bandwidth lossy gratings. With this technology we also demonstrate the direct writing of channel waveguides in commercial germania‐doped wafers without the use of photoresist and etching.

Stable single mode hybrid laser with high power and narrow linewidth

We describe hybrid lasers combining a semiconductor gain section and fiber cavity with integrated chirped Bragg reflector. These devices have produced output powers of 27.5 mW in a narrow linewidth (400 KHz) stable single longitudinal mode. The use of a chirped reflector to stabilize the single mode output, and correct grating orientation are described. The laser output has a side‐mode suppression ratio of over 55 dB at 27.5 mW output, and relative intensity noise (RIN) below 160 dB/Hz.

Volume holographic storage in hydrogen treated germano‐silicate glass

Strong permanent gratings (index change Δn∼3×10−3) have been formed in bulk hydrogen treated germano‐silicate glass with 242 nm exposure. Diffraction efficiencies of 6% and initial sensitivity (Δn/incident energy density) of 2×10−5 cm2/J have been obtained. The observed sensitivity is comparable to the values achieved in other holographic storage materials such as LiNbO3. It is estimated that by more uniform hydrogen loading of the sample, diffraction efficiencies of 100% can be obtained in 3 molu2009% GeO2 samples of only 175 μm thickness. These materials are potentially useful as fast access time (sub‐μs), high capacity (∼0.8 Tbits), robust, inexpensive write‐one‐read‐many storage media, narrow (subangstrom) linewidth optical filters, and other optical components.

ULTRAVIOLET LASER FABRICATION OF STRONG, NEARLY POLARIZATION-INDEPENDENT BRAGG REFLECTORS IN GERMANIUM-DOPED SILICA WAVEGUIDES ON SILICA SUBSTRATES

Strong Bragg reflectors (≳4 nm width) have been fabricated in Ge‐doped silica waveguides on silica substrates by ultraviolet (UV)‐induced refractive index change. Index changes in excess of 3×10−3 were obtained by deuterium sensitization. The passband quality, polarization dependence, and loss of the reflectors are reported.

GAP SOLITON PROPAGATION IN OPTICAL FIBER GRATINGS

Intense optical pulse propagation in a GeO2-doped silica glass fiber grating results in nonlinear pulse propagation velocities and increased transmission at wavelengths where the grating reflects light in the linear limit. These nonlinear pulse propagation effects are predicted by numerical simulations of gap soliton propagation. The large linear refractive-index variations used for the fiber gratings in these experiments permit the propagation of gap solitons in short lengths of fiber.

Volume gratings for holographic storage applications written in high-quality germanosilicate glass

Volume holographic gratings are written with ultraviolet light in high-optical-quality, commercially available Ge-doped silica films and in Ge-doped optical-fiber preform sections loaded with molecular hydrogen. In the film samples, peak refractive-index changes exceeding 10(-2) and a sensitivity (index change/absorbed energy density) of 0.4 × 10(-7) cm(3)/J are measured. Angular multiplexing of up to 51 gratings is demonstrated in the preform samples.

High-power mode-locked hybrid pulse source using two-section laser diodes

We describe a mode-locked hybrid pulse source with a two-section laser diode to obtain short mode-locked pulses (23 ps) with an average power of 7.8 mW, a high peak power of 137 mW, and a repetition rate of 2.51 GHz. The hybrid laser incorporates a two-section laser and an optical fiber cavity with an integrated Bragg reflector. The Bragg reflector controls the operating wavelength to subnanometer precision and also confines the bandwidth of the pulses so as to keep the time-bandwidth product below 1.

Packaged hybrid soliton pulse source results and 270 terabit.km/sec soliton transmission using sliding-frequency guiding filters

Summary form only given. A fully packaged hybrid soliton pulse source is described. Excellent stability and tuning characteristics are shown. Error free soliton transmission at 10 Gbit/s is achieved over 27,000 km using sliding-frequency guiding filters.

High power hybrid pulse source

We describe a mode-locked hybrid pulse source which produces short (23 ps) mode locked pulses with an average power of 7.8 mW, high peak power of 137 mW, at a repetition rate of 2.51 GHz. The source uses a two section laser diode to allow high peak power, in an optical fiber cavity with an integrated Bragg reflector. The Bragg reflector controls the operating wavelength to sub nanometer precision, and also confines the bandwidth of the pulses to keep the time bandwidth product below one.<<ETX>>