Abstract:
For setting the optical gain of an optical amplifier such as a Raman amplifier (1) that is connected in a wavelength division multiplexing (WDM) system, the gain of the amplifier is made dependent on the states of optical polarizers (4) connected to individual inputs (2) of a WDM multiplexer (3). The polarizers can be actively controlled by a device (10) connected to sense the output power of the Raman fiber (5) at different wavelengths. For an appropriate control the optical gain can be given any desired shape such as for example a reasonable flatness. The control of the polarization states of the WDM-channels allows for the use of a single wavelength pump source (8) of the amplifier, instead of the conventionally used multiwavelength source.
Abstract:
An optical monitor tap in fiber optical amplifiers is achieved in a configuration with internal input signal monitoring taps, in accordance with the principles of the invention, by placing the tap some distance into the actual optical amplifier active fiber. This allows the system to monitor the integrity of the amplifier without impairing the quality of the associated signal. In an illustrative embodiment of the present invention, the amplifier is generally comprised of a long piece of rare-earth material doped fiber to which a fiber optic pump source is coupled via a wavelength divisional multiplexer (WDM) coupler. The tap is placed at some distance from the input of the fiber amplifier. The distance should be small enough such that there has been amplification of the signal but not so much as to have the signal saturated or compressed.
Abstract:
A method (10) of changing operating mode of an optical amplifier in an amplifier chain in an optical network, the optical amplifier initially configured to operate in a first mode to apply a substantially constant first gain to an optical signal comprising a plurality of optical channels, the method comprising, after a time period unique to the optical amplifier within the amplifier chain (12), configuring the optical amplifier to operate in a second mode to apply a second gain to the optical signal so that the optical power of the optical signal is maintained at a target optical power dependent on a current plurality of optical channels in the optical signal (14).
Abstract:
Disclosed herein is a system (10) for measuring light induced transmission or reflection changes, in particular due to stimulated Raman emission. The system comprises a first light source (12) for generating a first light signal having a first wavelength, a second light source (14) for generating a second light signal having a second wavelength, an optical assembly (16) for superposing said first and second light signals at a sample location (18), and a detec tion means (24) for detecting a transmitted or reflected light signal, in particular a stimulated Raman signal caused by a Raman-active medium when located at said sample location. Here in at least one of the first and second light sources (12, 14) is one or both of actively control lable to emit a time controlled light pattern or operated substantially in CW mode and provid ed with an extra cavity modulation means (64) for generating a time controlled light pattern. The detection means (24) is capable of recording said transmitted or reflected light signal, in particular stimulated Raman signal, as a function of time.
Abstract:
A fiber ribbon cable that includes a plurality of ribbon tubes arranged in a pattern, wherein one of the ribbon tubes contains an optical fiber and an adjacent ribbon tube contains an electric heating element such that when heated the electric heating element is able to adjust the temperature of the optical fiber.
Abstract:
An amplified tunable source includes a short-cavity laser coupled to an optical amplifier for high power, spectrally shaped operation. The short-cavity laser is coupled to a quantum well semiconductor optical amplifier with two quantum states for broadened gain. Two preferred wavelength ranges of the amplified tunable source include 1200-1400nm and 800-1100nm. Also disclosed is the short cavity tunable laser coupled to a fiber amplifier. Various combinations of tunable optical filters with the amplified tunable source to reduce noise or improve spectral purity are presented.
Abstract:
A tunable source includes a short cavity laser with quantum well gain region supporting wide tuning range. The short cavity laser with a quantum well gain region, large free spectral range cavity, fast tuning response and single transverse, and longitudinal mode operation is disclosed. Both electrical and optical pumping of the short cavity laser are presented.
Abstract:
Optical systems employ a tunable source which includes a short cavity laser with a large free spectral range cavity, fast tuning response, and single transverse and longitudinal mode operation. Systems for optical spectroscopy with optimized scanning, a system for optical beam steering and a system for a tunable local oscillator are disclosed.