Various examples are provided related to single channel and multi-channel radio frequency (RF) steganography. In one example, a method includes generating an amplified spontaneous emission (ASE) broadband signal; spectrally slicing the ASE broad-band light to achieve taps for generating a dynamic photonic finite impulse response in an RF domain; generating a stealth-modulated broadband optical carrier by combining a stealth signal with the spectrally sliced ASE broadband light; passing the stealth-modulated broadband optical carrier to a dispersive medium to achieve the dynamic photonic FIR in the RF domain; and transmitting the stealth-modulated optical comb carrier via a transmission fiber. The ASE broadband light can have wavelength and intensity corresponding to background noise of a photonic system. In another example, a system for RF steganography includes a stealth transmitter. The stealth transmitter can generate and transmit the stealth-modulated optical comb carrier to a stealth receiver via a transmission fiber.

In order to enable easy adjustment of loss wavelength characteristics in accordance with the characteristics of a wavelength division multiplex optical signal, and the usage environment of an EDFA, etc., an equalizer 10 is provided with: a wavelength selection switch unit 20 that adds a loss profile that has been set to an inputted wavelength division multiplex optical signal, and outputs the same; and a setting unit 30 that sets the loss profile to a wavelength selection switch means on the basis of obtained setting information. The setting information is information for flattening the spectrum of the outputted wavelength division multiplex optical signal.

An optical remodulator includes: a polarization diversity modulator configured to modulate an input optical signal to generate an output optical signal by using a first optical modulator implemented for a first polarization state and a second optical modulator implemented for a second polarization state that is orthogonal to the first polarization state; a photo detector configured to optical-to-electrical convert the input optical signal or the output optical signal or both of the optical signals into an electric signal; and a drive signal generator configured to generate a first drive signal that drives the first optical modulator and a second drive signal that drives the second optical modulator based on the electric signal generated by the photo detector.

An optical remodulator includes: a polarization diversity modulator configured to modulate an input optical signal to generate an output optical signal by using a first optical modulator implemented for a first polarization state and a second optical modulator implemented for a second polarization state that is orthogonal to the first polarization state; a photo detector configured to optical-to-electrical convert the input optical signal or the output optical signal or both of the optical signals into an electric signal; and a drive signal generator configured to generate a first drive signal that drives the first optical modulator and a second drive signal that drives the second optical modulator based on the electric signal generated by the photo detector.

Various examples are provided related to single channel and multi-channel radio frequency (RF) steganography. In one example, a method includes generating an amplified spontaneous emission (ASE) broadband signal; spectrally slicing the ASE broadband light to achieve taps for generating a dynamic photonic finite impulse response in an RF domain; generating a stealth-modulated broadband optical carrier by combining a stealth signal with the spectrally sliced ASE broadband light; passing the stealth-modulated broadband optical carrier to a dispersive medium to achieve the dynamic photonic FIR in the RF domain; and transmitting the stealth-modulated optical comb carrier via a transmission fiber. The ASE broadband light can have wavelength and intensity corresponding to background noise of a photonic system. In another example, a system for RF steganography includes a stealth transmitter. The stealth transmitter can generate and transmit the stealth-modulated optical comb carrier to a stealth receiver via a transmission fiber.