Seeder for use with a fiber laser for generating an arbitrary shaped pulse, comprising an amplified spontaneous emission (ASE) source, a spectral filter and an arbitrary waveform generator (AWG) modulator, the ASE source for generating a continuous wave (CW) broadband pulse, the spectral filter being coupled with the ASE source for narrowing the CW broadband pulse, and the AWG modulator being coupled with the spectral filter for shaping the narrowed CW broadband pulse to an arbitrary pulse shape.

An arrangement for generating amplified spontaneous emission (ASE) over the combination of the C-band and L-band wavelength ranges is proposed, based on a reflective topology that reduces the number of individual components (compared with separate C-band and L-band ASE sources) required to generate the broadband ASE output. A pair of ASE generators are used, where at least one of the generators is configured to include a reflective element at a termination of the included gain fiber. The inclusion of the reflective element allows for the generated emission to pass through the gain fiber twice (emulating the operation of a conventional dual-stage ASE source). A long wavelength portion of the ASE created by a first ASE generator may be used as a seed input by the remaining ASE generator of the pair to further increase the efficiency of extending the ASE along the L-band wavelength range.

A fiber amplifier includes an isolator, a gain fiber to amplify an input laser signal, and an optical filter disposed between the isolator and the gain fiber. The optical filter transmits the laser signal and reflects amplified spontaneous emission (ASE) propagating from the gain fiber toward the isolator. The reflected ASE reenters the gain fiber and is absorbed by the gain fiber for amplifying the input laser signal. The optical filter in the amplifier can protect the usually expensive isolator and reduce potential damage to the gain fiber induced by fluctuation of the input laser signal power, as well as reduce potential photodarkening at the input of the gain fiber.

A fiber amplifier includes an isolator, a gain fiber to amplify an input laser signal, and an optical filter disposed between the isolator and the gain fiber. The optical filter transmits the laser signal and reflects amplified spontaneous emission (ASE) propagating from the gain fiber toward the isolator. The reflected ASE reenters the gain fiber and is absorbed by the gain fiber for amplifying the input laser signal. The optical filter in the amplifier can protect the usually expensive isolator and reduce potential damage to the gain fiber induced by fluctuation of the input laser signal power, as well as reduce potential photodarkening at the input of the gain fiber.

Aspects of the present disclosure describe systems, methods, and structures for providing bidirectional C-band and L-band transmission employing optical circulators which advantageously eliminates C\L WDM couplers while still blocking any backward amplified spontaneous emissions from optical amplifiers.

The present application is directed to an optical apparatus including an optical waveguide configured to receive an optical signal at an input wavelength. The apparatus also includes one or more optical pump sources connected to transmit pump light to the optical gain medium for the optical gain medium to amplify the optical signal. The apparatus also includes an optical feedback loop for a protection wavelength that includes the optical gain medium and at least a portion of the optical waveguide. A round-trip optical gain of the optical feedback loop is higher at an optical wavelength of the pump light than at the input wavelength less than unity in the presence of the optical signal. In addition, the round-trip gain of the optical feedback loop is greater than or equal to unity in the absence of the optical signal.