All-optical envelope detection for radio-over- fiber links using external optical injection of a DFB laser

Abstract

We outline a novel method performing all-optical envelope detection of radio-frequency signals for radio-over-fiber links. A high frequency modulated signal with a slower-varying envelope is injected into a DFB laser which, due to gain suppression effects, recovers only the envelope of the optical signal. We characterize the DFB gain suppression effect in terms of injected signal wavelength and power level requirements. System performance is assessed, including experimental bit-error rate results; these illustrate successful envelope detection for a 20 GHz carrier with ASK modulation operating at 2.5 Gbit/second. Preliminary results at 5.5 Gbit/s show significant potential for application in hybrid optical-wireless communications networks.

All-Optical Envelope Detection and Fiber Transmission of Wireless Signals by External Injection of a DFB Laser

“…With this system, XGM was previously [4] maximized when the wavelength of the injected optical signal into the DFB coincided with one of the spectral side lobes of the DFB output spectrum and was higher than the lase wavelength, and with an average injected power level in the interval dBm. In this experiment, the DFB wavelength was approximately 1551 nm; the following results were obtained with a WAP/ONU laser wavelength of 1553 nm and an average injected power level of 7 dBm into the DFB at RN.…”

“…We have demonstrated the application of the XGM effect in a distributed feedback (DFB) laser to achieve all-optical envelope detection of wireless signals and have reported on experimental characterization of such a device to obtain all-optical envelope detection of an amplitude-shift-keying (ASK) modulated signal with 20-GHz carrier frequency, carrying data at speeds up to 5 Gb/s [4]. In this letter, we report on further investigation of the application of the detection scheme in an optical access network environment simultaneously supporting passband radio-frequency-over-fiber (RFoF) and baseband transmission via a 70-km converged wireline and wireless signal transport optical link.…”

Photonic envelope detector for broadband wireless signals using a single Mach-Zehnder modulator and a fibre Bragg grating

“…To demodulate an ASK modulated carrier, envelope detection is needed. Recently envelope detection schemes have been proposed like for demodulating 10 Gbit/s ASK modulated 120 GHz carrier [1] using an electrical envelope detector and later performing the E/O conversion, or using an electro-absorption modulator (EAM) biased at its inflection point and external optical injection of a DFB laser [5], both of which involve complicated electronics and optical devices. In this paper a simplified photonic envelope detector with a single Mach-Zehnder modulator and a fibre Bragg grating is proposed.…”

Re-configurable digital receiver for optically envelope detected half cycle BPSK and MSK radio-on-fiber signals

“…Thus, optical envelope detection emerges as a promising technology to keep the complexity of optical components low as it requires only direct photodetection of the optical signal [8]. Moreover, complex RF mixers and local oscillator stages can be avoided as well [9,10]. The main challenge lies on the receiver side since emerging services from the convergence of wired and wireless networks may have diverse modulation formats and mixed bit rates.…”

“…Recently, optical envelope detection has been successfully demonstrated with various RF modulated signal types, including 5.5 Gbit/s amplitude shift-keying (ASK) [9], and 40 Mbaud 16 QAM and quadrature phase-shift-keying (QPSK) [10]. However, the advantages and benefits of digital receivers incorporated into optical envelope detection have not yet been investigated.…”