At&t Bell Laboratories

At+t Corp.

Yun C Chung

David John DiGiovanni

John L Zyskind

Julian Stone

James W Sulhoff

Jae S Lee

The present invention relates to a potentially inexpensive light for multi-channel wavelength-division-multiplexed (WDM) applications. The high-power amplified spontaneous emission (ASE) from a fiber amplifier, which is already in the optical fiber, is efficiently divided into many channels using a WDM demultiplexer. This 'spectrum-sliced' ASE is used as light sources for WDM systems rather than several wavelength-selected DFB lasers.

System for spectrum-sliced fiber amplifier light for multi-channel

A method for synchronizing an etalon to a preselected set of optical frequencies includes the step of generating a transmission spectrum for an etalon having a characteristic free spectral range that is a function of its effective length. The optical frequencies for the transmission spectrum are provided by two optical reference frequencies such as produced by a first and second frequency locked laser. The effective length of the etalon is set in relation to the optical reference frequencies.

Synchronized etalon filters

A tunable etalon filter is formed by placing mirrors on either side of a spacer of a material which has a relatively large rate of change of refractive index with temperature, and coupling the filter to a thermoelectric cooler to control the temperature of the spacer and, therefore, the index of refraction of the spacer. More specifically, the spacer can be a silicon wafer, or a wafer of zinc sulfide or zinc selenide. The mirrors can be formed of quarter wavelength layer pairs of dielectric coatings of high and low refractive index material. The thermoelectric cooler, which can be coupled to a heat sink, controls the temperature of the spacer by either heating or cooling the spacer. In operation the filter is coarse tuned by adjusting its angle relative to the angle of a received optical signal. It is then fine tuned to the signal by adjusting the temperature of the spacer. The advantages of this filter are: large tunability by angle tuning; fine tuning by temperature; large free-spectral-range; narrow passband; low insertion loss; and high reliability.

Tunable etalon filter

A compact all-fiber, electrically tunable ring laser includes a diode-pumped erbium-doped fiber amplifier. The frequency of the laser is tuned by a fiber Fabry-Perot (FFP) etalon that is electrically tuned. An in-line optical isolator is used in conjunction with the FFP to eliminate undesired reflections. A second FPP with a narrow free spectral range (FSR) can be used in conjunction with a first FFP with a wide FSR.

Electrically tunable fiber ring laser

A compact all-fiber, electrically tunable ring laser includes a diodepumped erbium-doped fiber amplifier. The frequency of the laser is tuned by a fiber Fabry-Perot(FFP) etalon that is electrically tuned. An in-line optical isolator is used in conjunction with the FFP to eliminate undesired reflections. A second FFP with a narrow free spectral range (FSR) can be used in conjunction with a first FFP with a wide FSR.

Frequency stabilization of a long wavelength semiconductor laser is achieved by employing the optogalvanic effect in a feedback control loop with the laser. Absolute references are obtained using noble gases such as argon (1.2 .mu.m to 1.4 .mu.m) and krypton (1.4 .mu.m to 1.6 .mu.m). Standard detection, feedback control and dithering lock-in techniques are used to insure proper frequency stabilization.

Frequency stabilization of long wavelength semiconductor laser via

Heterodyne and homodyne lightwave communication systems require transmitter optical sources and receiver local oscillators to be locked to a particular frequency. In accordance with the present invention, each transmitter laser and each receiver local oscillator laser is independently and locally stabilized to the same absolute frequency standard using species exhibiting atomic or molecular absorption lines in the wavelength range of interest. Frequency stabilization of the lasers is achieved by employing an optogalvanic effect element in a feedback control loop with the laser. Absolute frequency standards are obtained using gas discharge tubes containing, for example, noble gases such as argon (1.2 .mu.m to 1.4 .mu.m) and krypton (1.4 .mu.m to 1.6 .mu.m) and the like. Standard synchronous detection and feedback control techniques are used to insure proper long-term frequency stability.

Growing community of inventors

Aberdeen, NJ, United States of America

Yun C Chung