Device and method for generating frequency doubling single side band optical carrier millimeter waves

The invention discloses a device and a method for generating a terahertz wave based on a nested Mach-Zehnder modulator in the field of terahertz wireless communication. The device comprises a tunable light source, a radio frequency signal source, an electric branching unit, a first electric amplifier, an electric phase shifter, a second electric amplifier, the nested Mach-Zehnder modulator and a photoelectric detector. The method comprises the following steps that: a low-frequency sine wave signal output by the radio frequency signal source is divided into two paths by the electric branching unit; the two paths of signals are amplified by a first amplifier and a second amplifier and then respectively drive an upper arm sub-modulator and a lower arm sub-modulator of the nested Mach-Zehnder modulator; continuous light waves output by the tunable light source are input into the nested Mach-Zehnder modulator to modulate; the tuned continuous light waves are input into the photoelectric detector to carry out photoelectric conversion, and the output end of the photoelectric detector generates the terahertz wave which is 12fold as much as the frequency of the low-frequency sine wave signal by rationally adjusting modulation voltage and offset voltage of the nested Mach-Zehnder modulator. The device is simple in configuration, and the system cost and the requirements on the apparatus bandwidth are reduced.

Device and method for generating terahertz wave based on nested Mach-Zehnder modulator

The invention relates to a radio over fibre system, comprising a central station, a base station and a downlink link fibre. The central station comprises a laser, a DQPSK (Differential Quadrature Reference Phase Shift Keying) lithium niobate modulator and an erbium-doped fibre amplifier, which are connected in turn in series through an optical fibre. The DQPSK lithium niobate modulator is in a push-pull mode and used for generating quadruple harmonic wave including a cosine microwave signal and OFDM-QPSK (Orthogonal Frequency Division Multiplexing-Quadrature Reference Phase Shift Keying) data information side frequency component carried by the quadruple harmonic wave. By adjusting bias voltage, the base station can obtain a local oscillation signal for uplink receiving demodulation and a millimetre wave signal in required power and carrying the OFDM-QPSK data information and send the obtained millimetre wave signal through an antenna. In the invention, the DQPSK lithium niobate modulator composed of three Mach-Zehnder modulators is adopted to generate steady millimetre waves; an optical filter is saved; the structure is simplified; the cost is reduced; and the system is easy to realize commercial applications.

Radio over fibre system

A three-dimensional modulation ultra-wide band signal generation method based on a single double-drive modulator includes the steps of firstly, generating four routes of data pulse signals through a pulse signal source, and conducting pre-coding on each route of data pulse signal so that the voltage amplitude of the first data pulse signal and the voltage amplitude of the second data pulse signal can be larger than the voltage amplitude of the third data pulse signal and the voltage amplitude of the fourth data pulse signal; secondly, overlapping the first data pulse signal and the second data pulse signal and overlapping the third data pulse signal and the fourth data pulse signal to form two sets of overlapped signals; thirdly, conducting amplifying and phase offset processing on the overlapped signals and then loading the overlapped signals to the two ends of the double-drive Mach-Zehnder modulator so that three-dimensional UWB signals where coherence stack is conducted can be outputted by the double-drive Mach-Zehnder modulator. By means of the three-dimensional modulation ultra-wide band signal generation method, the bandwidth of the system and the dimension of the generated UWB signals can be effectively increased.

Three-dimensional modulation ultra-wide band signal generation method based on single double-drive modulator

Method for automatically compensating bias voltage of QPSK (quadri phase shift keying) lithium niobate modulator

In this paper, we proposed a novel architecture for full-duplex radio-over-fiber system. The optical single sideband mm-wave signal with frequency-doubling is generated via proper dc-bias on an integrated dual-parallel Mazh-Zehnder modulator, while the partial central carrier of the generated optical mm-wave signal is re-modulated with upstream data for uplink transmission.

Jianshe Li

Papers

Device and method for generating frequency doubling single side band optical carrier millimeter waves

A novel RoF architecture with optical single sideband mm-wave signal generation using frequency doubling and wavelength reuse for uplink connection