Photonic generation of microwave signal using a dual-wavelength
erbium-doped fiber ring laser with CMFBG filter and saturable absorber
Suchun Feng
a,
n
, Shaohua Lu
b
, Wanjing Peng
a
,QiLi
a
, Chunhui Qi
a
, Ting Feng
a
, Shuisheng Jian
a
a
Institute of Lightwave Technology, Key Lab of All Optical Network and Advanced Telecommunication of EMC, Beijing Jiaotong University, Beijing, Chi na
b
Safety Engineering Department, Beijing Vocational College of Labour and Social Security, Beijing, China
article info
Article history:
Received 17 May 2012
Received in revised form
31 July 2012
Accepted 2 August 2012
Available online 24 August 2012
Keywords:
Microwave generation
Single-longitudinal-mode
CMFBG filter
abstract
A simple approach for photonic generation of microwave signal using a dual-wavelength single-
longitudinal-mode (SLM) erbium-doped fiber (EDF) ring laser is proposed and demonstrated. For the
first time as we know, a chirped moire
´
fiber Bragg grating (CMFBG) filter with ultra-narrow
transmission band and a chirped fiber Bragg grating (FBG) are used to select the laser longitudinal
mode. The stable SLM operation of the fiber laser is guaranteed by the combination of the CMFBG filter
and 3 m unpumped EDF acting as a saturable absorber. Stable dual-wavelength SLM fiber lase r with a
wavelength spacing of approximately 0.140 nm is experimentally realized. By beating the dual-
wavelength fiber laser at a photodetector, photonic generation of microwave signal at 17.682 GHz is
successfully obtained.
& 2012 Elsevier Ltd. All rights reserved.
1. Introduction
Photonic generation of microwave signals has attracted con-
siderable interests for their applications in various fields such as
radio-over-fiber networks, broadband wireless access network,
sensor networks and so on. In the last few years, there are
numerous techniques for the photonic generation of microwave
signals, which can be classified into four categories [1]: (a) optical
injection locking, (b) optical phase-lock loop, (c) microwave
generation using external modulation, and (d) dual-wavelength
single-longitudinal-mode (SLM) laser source. Recently, more and
more researchers have paid attention to photonic generation of
microwave signals using dual-wavelength SLM fiber laser sources.
It is difficult to obtain simultaneous multi-wavelength lasing at
room temperature in erbium-doped fiber (EDF) lasers because
EDF is the primary homogeneous gain medium. Chen et al. [2]
proposed dual-wavelength SLM laser utilizing an ultranarrow
dual-transmission-peak bandpass filter in a ring cavity. They also
demonstrated the dual-wavelength SLM lasers in linear laser
cavity [3–6]. Nevertheless, the required bandpass filters must
be specially designed with the complicated equivalent phase
shift technique and the spacing between the two transmission
peak wavelengths is restricted by the reflection bandwidth of the
uniform fiber Bragg grating (FBG). Liu [7] also proposed the
similar technique to realize the dual-wavelength SLM laser
in a linear laser cavity. Li et al. [8] proposed dual-wavelength
emission from cascaded distributed feedback fiber lasers, but the
FBG need to be specially fabricated for the lack of photosensitivity
of the phosphate glass fiber. Villanueva et al. [9] obtained dual-
wavelength DFB fiber laser by introducing two local phase shifts
generated by piezoelectric transducers in the periodic structure of
an erbium-doped FBG. Polarization maintaining FBG or FBG with
birefringence is also used to achieve the SLM dual-wavelength
fiber lasers utilizing the polarization hole burning (PHB) effect
[10–12]. The Fabry–Pe
´
rot etalon filters with narrow transmission
bandwidth or phase-shifted FBG based on the uniform FBG can be
used to obtain the SLM dual-wavelength fiber lasers [13–18], but
the spacing between the two transmission peak wavelengths is
also restricted by the reflection bandwidth of the FBG. Phase-
shifted chirped FBG is also used to achieve the tunable SLM dual-
wavelength fiber lasers [19–21]. Superimposed chirped FBG
(SCFBG) or named chirped moire
´
FBG (CMFBG), which can also
be seen as the phase-shifted chirped FBG [22] has ultra-narrow
transmission band, has been used to achieve multi-wavelength
SLM lasing in the photosensitive erbium–ytterbium co-doped
fiber [23]. Sun et al. [24] presented SLM dual-wavelength fiber
ring laser using Sagnac filters and a saturable absorber with
complicated configuration and operating principle. Qian et al.
[25] demonstrated SLM dual-wavelength fiber ring laser using the
Mach–Zehnder comb filter incorporating with the counter-
propagation of the two light beams. Chen et al. [26] also proposed
SLM dual-wavelength fiber ring laser using the Mach–Zehnder
comb filter and a saturable absorber. However, we all know that
the Sagnac or Mach–Zehnder comb filter is more sensitive to
Contents lists available at SciVerse ScienceDirect
journal homepage: www.elsevier.com/locate/optlastec
Optics & Laser Techn ology
0030-3992/$ - see front matter & 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.optlastec.2012.08.002
n
Corresponding author. Tel./fax: þ 86 10 51683625.
E-mail address: fengsuchun@gmail.com (S. Feng).
Optics & Laser Technology 45 (2013) 32–36