Stephen R. Chinn

High‐power strained‐layer InGaAs/AlGaAs tapered traveling wave amplifier

High power, nearly diffraction‐limited cw performance has been obtained from a traveling wave amplifier, fabricated in a strained‐layer InGaAs/AlGaAs laser structure, with a laterally tapered gain region and with a cavity‐spoiling feature to prevent laser oscillation. The input beam diffracts as it propagates, efficiently filling the tapered active region. For input optical power of 85 mW from a Ti:sapphire laser, total cw output of 1.44 W has been achieved with 1.28 W in a central lobe with width less than 1.2 times the diffraction limit at 977 nm wavelength. Only 15 mW of power incident on the amplifier was sufficient to provide 1 W output into the central lobe.

High-power, strained-layer amplifiers and lasers with tapered gain regions

Laterally tapered gain regions designed to accommodate the diffraction of narrow single-lobe beams that have been used in both optical amplifiers and lasers are described. Amplifier output power of 3.5 W with 3.1 W in a 1.05 times diffraction-limited lobe and laser output power of over 4 W with approximately half the power in a 1.7 times diffraction-limited lobe have been achieved.<<ETX>>

Effects of mirror reflectivity in a distributed-feedback laser

The linear coupled-wave analysis of a distributed-feedback laser is presented for nonzero reflectivity at the ends of the lasing medium. Numerical results are given for the case of real coupling coefficients and the threshold behavior, as the reflectivity effects dominate, is described.

Sensitivity of optically preamplified DPSK receivers with Fabry-Perot filters

The error-rate performance of a DPSK lightwave receiver having an optical amplifier followed by a Fabry-Perot filter and delay-line demodulator is analyzed. Receivers with sampling and with integrate-and-dump threshold comparison are compared to the well-known result for a matched optical filter. The Fabry-Perot filter decreases the sensitivity at 10/sup -9/ error-rate from 20 to 24.5 photons/b with optimum optical filter bandwidth and postdetection integration time.

40-GHz pulse train generation using soliton compression of a Mach-Zehnder modulator output

We demonstrate 40-GHz soliton pulse train generation using nonlinear compression of the output of a Mach-Zehnder modulator. This source generates transform-limited pulses at twice the RF drive frequency, requires less than V/sub /spl pi// drive level, is tunable in wavelength (over the entire EDFA bandwidth), and is tunable in repetition rate.<<ETX>>

100-GHz soliton pulse train generation using soliton compression of two phase side bands from a single DFB laser

A 100-GHz soliton pulse train, with the potential of very low timing jitter, is generated using soliton compression of the beat signal between two optical carriers. The optical carriers are obtained by optically filtering out the third-order sidebands generated from a single DFB laser and a LiNbO/sub 3/ electro-optic phase modulator driven at 16.9 GHz.<<ETX>>

Slab-coupled 1.3-μm semiconductor laser with single-spatial large-diameter mode

A high brightness semiconductor diode laser structure, which utilizes a slab-coupled optical waveguide region to achieve several potentially important advances in performance, is proposed and experimentally demonstrated using a simple rib waveguide in an InGaAsP-InP quantum-well structure operating at 1.3-/spl mu/m wavelength. These lasers operate in a large low-aspect-ratio lowest-order spatial mode, which can be butt coupled to a single-mode fiber with high coupling efficiency.

Low‐threshold cw LiNdP4O12 laser

We have studied cw room‐temperature lasing behavior of LiNdP4O12. A threshold of 360‐μW optical excitation power at 0.582‐μm wavelength was measured, with 18% power conversion efficiency to 1.048‐μm radiation at 1‐mW output. The crystal structure is found to be monoclinic (C2/c) rather than orthorhombic as previously reported.

Picosecond-accuracy all-optical bit phase sensing using a nonlinear optical loop mirror

We demonstrate picosecond-accuracy bit phase comparison using a nonlinear optical loop mirror. We use this all-optical bit phase comparator to synchronize an external cavity modelocked diode laser operating at 10-GHz to a soliton compression source operating at 10-GHz using an electrooptic phase lock loop. We believe this is the first demonstration of soliton compression source synchronization. The holding range of the phase lock loop is /spl plusmn/20 MHz, and is limited by the modelocking bandwidth of the external cavity laser. Clock acquisition time is dominated by the latency of the nonlinear optical loop mirror.<<ETX>>

Distributed feedback Pb1−xSnxTe double‐heterostructure lasers

Distributed feedback laser operation is demonstrated in stripe‐geometry Pb1−x Sn x Te double heterostructuresgrown by molecular‐beam epitaxy. The grating of 1.1 μm periodicity operates in first order near 745 cm−1 (13.4 μm) under pulsed conditions in a limited range of heat‐sink temperatuers (∼30–65 K) where both gain and the Bragg reflection condition can be achieved. The guide index n g ≃6.1 is consistent with theoretical estimates. In Pb1−x Sn x Te DH devices, by corrugating the surface after all epitaxy is completed, a large coupling coefficient for Bragg reflection can be achieved because the last confining layer can be made very thin and the grating aspect ratio large.