Semiconductor optical amplifier-based multi-wavelength ring laser utilizing photonic crystal fiber

Room temperature multiwavelength erbium-doped fiber ring laser using a highly nonlinear photonic crystal fiber

Tunable multiwavelength Erbium-doped fiber laser based on in-fiber Fabry-Perot interferometer fiber Bragg gratings in linear and ring cavity configurations

A new stable dual-wavelength fiber ring laser based on Raman amplification, deploying a dispersion-compensating fiber (DCF) as gain medium, is introduced. The gain competition effects in the fiber Raman amplification are mitigated because the two emission lines, selected by fiber Bragg grating within the resonant ring cavities, travel in opposite directions through the gain medium. The experimental results confirm that the novel multiwavelength ring laser source is stable and it offers a high optical signal-to-noise ratio.

In this paper, we have proposed and demonstrated a multi-wavelength laser source based on a semiconductor optical amplifier (SOA) and optical filter module. The optical filter module is composed from a polarizer (P), polarization controller (PC), polarization maintaining fiber (PMF) and mirror. The multi-wavelength laser is generated by constructing SOA and optical filter module in a loop. The output wavelengths are determined by an optical filter module. The Experimental results revealed that a stable multi-wavelength lasing with 0.27 nm wavelength spacing is achieved at room temperature. Moreover, the proposed method is cost effective compared to the previously proposed schemes.

A spacing-tunable multiwavelength fiber laser source is demonstrated by using a semiconductor optical amplifier and a novel free-spectral-range tunable Fabry-Perot filter with superimposed, chirped-fiber Bragg gratings. Continuous tuning of 0.3-0.6 nm has been realized.

Four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs) has several important features, such as, high speed and high FWM conversion efficiency as well as optical demultiplexing (DEMUX) (Mecozzi et al., 1995; Mecozzi & Mrk, 1997; Das et al., 2000). The are several applications of FWM in SOAs for all-optical devices, such as, wavelength converters (Vahala et al., 1996), optical samplers (Inoue & Kawaguchi, 1998), optical phase conjugators (Kikuchi & Matsumura, 1998) and optical multiplexers/demultiplexers (Kawanishi et al., 1997; Kawanishi et al., 1994; Morioka et al., 1996; Uchiyama et al., 1998; Tomkos et al., 1999; Kirita et al., 1998; Buxens et al., 2000) have been demonstrated for optical communication systems. When a pulse of a time-multiplexed signal train (for example, a probe pulse) and a pump pulse are injected simultaneously into an SOA, gain and refractive index in the SOA are modulated and an FWM signal is generated by the modulations. Thus, we can obtain a demultiplexed signal as an FWM signal at the output of SOA. All-optical demultiplexing has been experimentally demonstrated up to 200 Gbit/s (Morioka et al., 1996). Tomkos et al., (Tomkos et al., 1999) suggested a number of ways to improve the performance of the dual-pump demultiplexer at 40 Gbit/s as follows; adjustment of the input wavelengths at the peak gain wavelength of the SOA under saturation conditions, the use of higher pump power at the input of the device, or/and the use of pulsed pumps with short pulsewidths. For the higher bit-rate, the overlap of the input to the FWM signal pulses may appear both in the time and spectral domain. The pattern effect may also appear in the FWM signal due to the slow components of the optical nonlinearities in SOAs (Saleh & Habbab, 1990). These effects degrade the usefulness of the FWM in SOAs as a practical DEMUX device in optical network/ communication systems. Therefore, it is very important to analysis the optical DEMUX characteristics based on FWM in SOAs for the ultrafast multi-bit input optical pulses.

Remote laser in air based on amplified spontaneous emission (ASE) has produced rather well-collimated coherent beams in both backward and forward propagation directions, opening up possibilities for new remote sensing approaches. The remote ASE-based lasers were shown to enable operation either at ~391 and 337 nm using molecular nitrogen or at ~845 nm using molecular oxygen as gain medium, depending on the employed pump lasers. To date, a multi-wavelength laser in air that allows for dynamically switching the operating wavelength has not yet been achieved, although this type of laser is certainly of high importance for detecting multiple hazard gases. In this Letter, we demonstrate, for the first time to our knowledge, a harmonic-seeded switchable multi-wavelength laser in air driven by intense mid-infrared femtosecond laser pulses. Furthermore, population inversion in the multi-wavelength remote laser occurs at an ultrafast time-scale (i.e., less than ~200 fs) owing to direct formation of excited molecular nitrogen ions by strong-field ionization of inner-valence electrons, which is fundamentally different from the previously reported pumping mechanisms based either on electron recombination of ionized molecular nitrogen or on resonant two-photon excitation of atomic oxygen fragments resulting from resonant two-photon dissociation of molecular oxygen. The bright multi-wavelength laser in air opens the perspective for remote detection of multiple pollutants based on nonlinear spectroscopy.

Based on a piece of highly-nonlinear near-zero-dispersion-flattened photonic crystal fiber (PCF), a broadly tunable multiwavelength erbium-doped fiber laser is proposed by using a bi-directionally pumping scheme. This kind of PCF induces the modulation-instability-assisted four-wave mixing to generate new wavelengths. The proposed laser with excellent stability is tunable and switchable by adjusting the fiber Bragg gratings and the variable optical attenuators. The outstanding merits of the proposed multiwavelength laser are the flexible tuning and the ultrabroad spectral range over 150 nm. Especially, the proposed laser source can work at the wavelength of less than 1460 nm, overcoming the limit of gain bandwidth of erbium-doped fiber.

In this paper, the development of loop mirror multi-wavelength Brillouin fiber laser utilizing semiconductor optical amplifier and fiber Bragg grating is successfully demonstrated. A multi-wavelength BFL structure employs a single mode fiber that acts as the gain medium, while the fiber Bragg grating act to reflect the signals and semiconductor optical amplifier is used to amplify the signal are employed to produce multiple channels. The implementation of difference parameter for semiconductor optical amplifier driven current, Brillouin pump power, Brillouin pump wavelength and length of single mode fiber, plays an important role in producing the multiple channels. The highest number of channels which is 15 achieved once 9 km of SMF length, semiconductor optical amplifier current at 800mA and low Brillouin pump power at -12 dBm are utilized in the laser structure. Furthermore, the implementation of semiconductor optical amplifier and reflectivity of fiber Bragg grating in Brillouin fiber laser structure gives a better performance in producing the multiple channels.

A 16-channel electroabsorption modulated tunable multi-wavelength DFB laser array is proposed and experimentally demonstrated. The sixteen DFB lasers, each with a wavelength spacing of 100 GHz, are arranged in a 4 × 4 matrix. The wavelengths are designed using an interleaving scheme to reduce grating crosstalk. The grating is designed and fabricated using the reconstruction equivalent chirp (REC) technique to simplify the grating fabrication and ensure precise wavelength control. The electroabsorption modulator and the tunable multi-wavelength laser array share the same active layer to reduce fabrication complexity and costs. Wavelength tuning is achieved by selecting the active laser without altering the thermoelectric cooler (TEC). Consequently, 16 channels with 100 GHz spacing are obtained, each operating in good single-mode properties with SMSRs of above 45 dB. The average wavelength spacing is 106.1 GHz, and only 6.1 GHz deviated from the design. The semiconductor optical amplifier (SOA) is integrated to compensate for the frequency chirp and amplify the output power, thus enabling long-distance transmission. The output power is amplified to over 18 mW with a 150 mA current injected into the SOA. The 3-dB bandwidth of the EAM exceeds 20 GHz, producing clear 25 Gb/s back-to-back eye diagrams with mask margins over 40% for the 16 channels. With the assistance of the chirp compensation by the SOA, the eye diagrams of the 16 channels remain clear after 10 km of transmission. Due to the superior performance, the proposed device is promising for use in DWDM systems, particularly in applications requiring fast channel switching, such as optical packet switching and NG-PON2 technology.

Tunable 12×10 GHz mode-locked semiconductor fiber laser incorporating a Mach-Zehnder interferometer filter

A multi-wavelength Brillouin fiber laser with the implementation of reflective fiber Bragg grating is developed. In this ring cavity architecture, the fiber laser system is performed by the stimulated Brillouin scattering effect and four-wave mixing process. An improvement in the number Brillouin Stokes signal and average of the optical signal to noise ratio were generated through the reflection process of fiber Bragg grating. Due to the optimization of output coupling ratio from 10% to 60%, the highest Brillouin Stokes signal of 17 and average optical signal to noise ratio of 14.7 dB were recorded at 60% of the output coupling ratio. The amplified Brillouin pump power of 16.5 dBm at 1550 nm of Brillouin pump wavelength was injected into the laser system. A constant line spacing of 0.08 nm at each of the Brillouin Stokes signals was also recorded.

To enhance the functionality and flexibility of a multiwavelength fiber laser, characteristics such as the tunability of the lasing wavelength, the wavelength spacing and the number of channels should be investigated simultaneously. We have demonstrated a channel spacing and wavelength tunable multiwavelength fiber ring laser based on semiconductor optical amplifier and a novel tunable polarization-diversity loop configuration (PDLC)-based comb filter. The tunable PDLC-based comb filter would be composed of a polarization beam splitter and three wave plates (one quarter wave plate and two half wave plates) and a polarization differential delay line (DDL). Channel spacing can be controlled continuously by using a motorized polarization differential delay line. And wavelength can be simultaneously changed by controlling wave plates. The PDLC-based comb filter has the advantages of the input polarization independence and simple tunability. By employing the comb filter in the laser system, multiwavelength operation of up to 25 laser lines with the signal-to-noise ratio over 25 dB and 0.8 nm wavelength spacing has been demonstrated at room temperature. Also, we could achieve the increased output channel power of the laser while reducing the number of channels. The results show that the multiwavelength operation is even and stable. And we could achieve the output spectra of tuned wavebands with channel spacing of 1.6 nm and 0.4 nm when the semiconductor optical amplifier is driven with the injection current of 160 mA while adjusting a half-wave plate at each tuning set. As a result, the shift of lasing wavelength and wavelength spacing were continuously controllable in this system.

This investigation demonstrates a stable multiwavelength fiber ring laser with ultra-narrow wavelength spacing using a semiconductor optical amplifier (SOA). A delay interferometer and a mirror are used as a double-pass interferometer to improve the signal-to-noise ratio in this experiment. Up to 181 stable lasing wavelengths with a wavelength spacing of 10.7 GHz and a signal-to-noise ratio of over 24 dB are produced at room temperature.

Summary form only given. An overview is presented of the progress in design and characteristics of semiconductor optical amplifiers (SOA) for 1310, 1400 and 1550 nm operation in fiber optical transmission systems. The technology and performance of SOAs will be discussed with respect to optical gain, noise figure, saturation output power and polarization (in-) dependent behavior. The use of both strained quantum wells and bulk tensile material will be discussed in view of obtaining polarization independent behavior. Gain clamping in SOAs has been shown to improve the linearity performance especially for analogue signal transmission. The SOA technology has been demonstrated for optical pre-amplification, in-line application and optical booster applications. DWDM experiments using SOAs in up to 20 Gbit/s systems in short- and medium-distance transmission will be highlighted. Also, SOAs have been used in optical demultiplexing from 40 Gbit/s down to 10 Gbit/s RZ signals using its phase properties and in integrated photonic devices like multiwavelength lasers.