A processor of an apparatus is configured to apply one or more control algorithms using estimated data to adjust the one or more control parameters of a section of an optical fiber network. The estimated data are derived from measurements of optical signals in the section and from knowledge of the section. The estimated data is a function of optical nonlinearity and of amplified spontaneous emission.

According to examples, a channel checker optical time-domain reflectometer (OTDR) may include a laser source to emit a laser beam. An optical switch may be optically connected to the laser source to receive the laser beam and to selectively transmit the laser beam to a circulator that is optically connected to a device under test (DUT). A first coupler may be optically connected to a first photodiode and to the circulator. A second coupler may be optically connected to the first coupler, the optical switch, and a second photodiode.

According to examples, a channel checker optical time-domain reflectometer (OTDR) may include a laser source to emit a laser beam. An optical switch may be optically connected to the laser source to receive the laser beam and to selectively transmit the laser beam to a circulator that is optically connected to a device under test (DUT). A first coupler may be optically connected to a first photodiode and to the circulator. A second coupler may be optically connected to the first coupler, the optical switch, and a second photodiode.

Methods, apparatus, and systems are disclosed for implementing a fiber optic reflectance standard (FORS) for testing and/or calibration of a test instrument (TI), which provides a traceable means to calibrate the making optical return loss measurements (ORLM). The apparatus for implementing the FORS may include an optical splitter, first and second optical inputs coupled to the optical splitter, and an optical fiber having first and second ends, and coupled to the optical splitter at the first end of the optical fiber. Furthermore, the apparatus includes an attenuator (e.g., a mechanical attenuator) configured to contain a portion of the optical fiber between the first and second ends and selectively attenuate optical signal gain of the optical fiber. The testing and/or calibration results in an uncertainty that is at least four times better than a typical test instrument.

The disclosed systems and methods support addition of bands to a multi-band optical interface. The systems and methods can include a multi-band interface device for optical networks. The device can include a multi-band optical amplifier, a C-Band Add/Drop multiplexer, an L-Band Add/Drop multiplexer and an amplifier noise source. The multi-band optical amplifier can be connected to the C-Band Add/Drop multiplexer and connected to the L-Band Add/Drop multiplexer through the amplifier noise source. The amplifier noise source be configured to generate a combination of bulk noise and an input transmission received from the L-Band Add/Drop multiplexer. The gain of the amplifier noise source can depend on the power of the received input transmission. The power of the received input transmission can be increased over a period of time, transitioning the amplifier noise source from acting as a bulk noise source to acting an amplifier.

An RF frequency converter with equalization may include a first E/O modulator configured to modulate an optical carrier signal based upon an RF input signal having a first frequency, and a SBS medium coupled to the first E/O modulator. The RF frequency converter may have a second E/O modulator configured to modulate the optical carrier signal based upon an equalizing function waveform, and a third E/O modulator coupled between the first E/O modulator and the SBS medium. The third E/O modulator may be configured to modulate the optical carrier signal with a reference signal. The RF frequency converter may include an optical circulator coupled to the SBS medium and the second E/O modulator, and a photodetector coupled to the optical circulator and configured to generate an equalized RF output signal having a replica of the RF input signal at a second frequency based upon the reference signal.

An RF frequency converter with equalization may include a first E/O modulator configured to modulate an optical carrier signal based upon an RF input signal having a first frequency, and a SBS medium coupled to the first E/O modulator. The RF frequency converter may have a second E/O modulator configured to modulate the optical carrier signal based upon an equalizing function waveform, and a third E/O modulator coupled between the first E/O modulator and the SBS medium. The third E/O modulator may be configured to modulate the optical carrier signal with a reference signal. The RF frequency converter may include an optical circulator coupled to the SBS medium and the second E/O modulator, and a photodetector coupled to the optical circulator and configured to generate an equalized RF output signal having a replica of the RF input signal at a second frequency based upon the reference signal.

Techniques for transmitting an optical signal through optical fiber with an improved cost effective stimulated Brillouin scattering (SBS) suppression include externally modulating a light beam emitted from a light source with a high frequency signal. The light beam is also modulated externally with an RF information-carrying signal. The high frequency signals are at least twice a highest frequency of the RF signal. The high frequency signals modulating the light source can be gain and phase adjusted by the first set of gain and phase control circuit to achieve a targeted spectrum shape. The adjusted high frequency signals then are split, providing a portion of the split signals to modulate the light source and another portion of the split signals to the second set of phase and gain control circuit for adjusting a phase/gain. The output of second set of phase and gain control circuits can be applied to the external modulator to eliminate intensity modulation caused by the corresponding high frequency signals that modulate the light source. The spread spectrum for SBS suppression or the optical transmitter's SNR is further improved by cancelling a beat between SBS suppression modulation tones and out of band distortion spectrum of information bearing RF signal.

Techniques for transmitting an optical signal through optical fiber with an improved cost effective stimulated Brillouin scattering (SBS) suppression include externally modulating a light beam emitted from a light source with a high frequency signal. The light beam is also modulated externally with an RF information-carrying signal. The high frequency signals are at least twice a highest frequency of the RF signal. The high frequency signals modulating the light source can be gain and phase adjusted by the first set of gain and phase control circuit to achieve a targeted spectrum shape. The adjusted high frequency signals then are split, providing a portion of the split signals to modulate the light source and another portion of the split signals to the second set of phase and gain control circuit for adjusting a phase/gain. The output of second set of phase and gain control circuits can be applied to the external modulator to eliminate intensity modulation caused by the corresponding high frequency signals that modulate the light source. The spread spectrum for SBS suppression or the optical transmitter's SNR is further improved by cancelling a beat between SBS suppression modulation tones and out of band distortion spectrum of information bearing RF signal.

A wavelength conversion apparatus includes a multiplexer-demultiplexer configured to include a first port, a second port, and a third port, a looped non-linear optical medium including one end that is optically connected to the second port of the multiplexer-demultiplexer, another end that is optically connected to the third port of the multiplexer-demultiplexer, and a main axis that rotates by 90 degrees between the second port and the third port, a first filter configured to be inserted into the non-linear optical medium, and remove stimulated Brillouin backscattered light that is bidirectionally generated in the non-linear optical medium, and a second filter configured to take out, from output light that is multiplexed in the multiplexer-demultiplexer after propagating through the non-linear optical medium and is outputted from the first port, conversion light having a third frequency different from the frequencies of a signal light and an excitation light.