Single-mode and tunable VCSELs in the near- to mid-infrared

Single-mode, long-wavelength vertical-cavity surface-emitting lasers （VCSELs） in the near- to mid-infrared covering the wavelength range from 1.3 to 2.3 μm are presented. This wide spectral emission range opens applications in gas sensing and optical interconnects. All these lasers are monolithically grown in the InGaAlAs-InP material system utilizing a buried tunnel junction （BTJ） as current aperture. Fabricated with a novel high-speed design with reduced parasitics, bandwidths in excess of 10 GHz at 1.3 and 1.55 μm have been achieved. Therefore, the coarse wavelength division multiplexing （CWDM） wavelength range of 1.3 to 1.6 μm at 10 Gb/s can be accomplished with one technology. Error-free data-transmission at 10 Gb/s over a fiber link of 20 km is demonstrated. One-dimensional arrays have been fabricated with emission wavelengths addressable by current tuning. Micro-electro-mechanical system （MEMS） tunable devices provide an extended tuning range in excess of 50 nm with high spectral purity. All these devices feature continuous-wave （CW） operation with typical single-mode output powers exceeding 1 mW. The operation voltage is around 1 - 1.5 V and power consumption is as low as 10 - 20 mW. Furthermore, we have also developed VCSELs based on GaSb, targeting functionality of tunable diode laser spectroscopy （TDLS） applying a 1.84-μm VCSEL. at the wavelength range from 2.3 to 3.0 μm. The systems is shown by presenting a laser hygrometer     

Single-mode and tunable VCSELs in the near-to mid-infrared Invited Paper

Single-mode,long-wavelength vertical-cavity surface-emitting lasers(VCSELs)in the near-to mid-infrared covering the wavelength range from 1.3 to 2.3μm are presented.This wide spectral emission range opens applications in gas sensing and optical interconnects.All these lasers are monolithically grown in the InGaAlAs-InP material system utilizing a buried tunnel junction(BTJ)as current aperture.Fabricated with a novel high-speed design with reduced parasitics,bandwidths in excess of 10 GHz at 1.3 and 1.55μm have been achieved.Therefore,the coarse wavelength division multiplexing(CWDM)wavelength range of 1.3 to 1.6μm at 10 Gb/s can be accomplished with one technology.Error-free data-transmission at 10 Gb/s over a fiber link of 20 km is demonstrated.One-dimensional arrays have been fabricated with emission wavelengths addressable by current tuning.Micro-electro-mechanical system(MEMS)tunable devices provide an extended tuning range in excess of 50 nm with high spectral purity.All these devices feature continuous-wave(CW)operation with typical single-mode output powers exceeding 1 mW.The operation voltage is around 1-1.5 V and power consumption is as low as 10-20 mW.Furthermore,we have also developed VCSELs based on GaSb,targeting at the wavelength range from 2.3 to 3.0μm.The functionality of tunable diode laser spectroscopy(TDLS)systems is shown by presenting a laser hygrometer applying a 1.84-μm VCSEL.     

Single-mode and tunable VCSELs in the near- to mid-infraredInvited Paper

Single-mode, long-wavelength vertical-cavity surface-emitting lasers (VCSELs) in the near- to mid-infrared covering the wavelength range from 1.3 to 2.3μm are presented. This wide spectral emission range opens applications in gas sensing and optical interconnects. All these lasers are monolithically grown in the InGaA1As-InP material system utilizing a buried tunnel junction (BTJ) as current aperture. Fabricated with a novel high-speed design with reduced parasitics, bandwidths in excess of 10 GHz at 1.3 and 1.55 μm have been achieved. Therefore, the coarse wavelength division multiplexing (CWDM) wavelength range of 1.3 to 1.6 μm at 10 Gb/s can be accomplished with one technology. Error-free data-transmission at 10 Gb/s over a fiber link of 20 km is demonstrated. One-dimensional arrays have been fabricated with emission wavelengths addressable by current tuning. Micro-electro-mechanical system (MEMS) tunable devices provide an extended tuning range in excess of 50 nm with high spectral purity. All these devices feature continuous-wave (CW) operation with typical single-mode output powers exceeding 1 mW. The operation voltage is around 1 - 1.5 V and power consumption is as low as 10 - 20 mW. Furthermore, we have also developed VCSELs based on GaSb, targeting at the wavelength range from 2.3 to 3.0 μm. The functionality of tunable diode laser spectroscopy (TDLS) systems is shown by presenting a laser hygrometer applying a 1.84-μm VCSEL.     

A Dual-Wavelength Cladding-Pumped Er^3＋/Yb^3＋ Codoped Fibre Laser System with More Than 2 W Output and Tunable Wavelength Spacing

A dual-wavelength laser system with wideband tunable wavelength spacing and more than 2 W output power is proposed and demonstrated. The operation principle of the laser system is based on the saturation gain characteristic of a cladding-pumped Era＋ /yba＋ co-doped fibre amplifier combining with a wideband tunable fibre laser with fiat power spectrum. The tuning range of the wavelength spacing is continuous within a 35 nm spectral range, and the power difference between both lasing wavelengths can be easily adjusted and controlled by a variable optical attenuator. The total output power can approximately keep unchangeable when the wavelength spacing and the power difference between both lasing wavelengths are continuously tuned and changed. The maximum total output power of the laser system is about 2.22 W.     

Self-seeded quantum-dash laser based 5 m–128 Gb/s indoor free-space optical communication

We demonstrate an indoor 5 m free-space optical wireless coherent communication in mid L-band(1606.7 nm)by employing a tunable self-seeded InAs/InGaAlAs/InP quantum-dash(Qdash) laser as a subcarrier generator for 128 Gb/s dual-polarization quadrature phase shift keying(DP-QPSK) modulation signal. The bare Qdash laser diode displays ~6 nm self-locked Fabry–Perot mode tunability with ~30 dB side mode suppression ratio(SMSR) and ~10 dBm mode power across the tuning range, thus encompassing ~10 modes with an achievable capacity of 1.28 Tb/s(10 × 128 Gb∕s) and potentially qualifying the source requirements for future access networks.     

All-fiber,wavelength-tunable ultrafast praseodymium fiber laser

The interest in tunable ultrafast fiber lasers operating in the 1.3 μm region has seen a significant increase due to rising demands for bandwidth as well as the zero-dispersion characteristic of silica fibers in this wavelength region. In this work, a tunable mode-locked praseodymium-doped fluoride fiber(PDFF) laser using single-walled carbon nanotubes as a saturable absorber is demonstrated. The mode-locked pulses are generated at a central wavelength of 1302 nm with a pulse repetition rate of 5.92 MHz and pulse width of 1.13 ps. The tunability of the mode-locked PDFF laser covers a tuning range of 11 nm.     

A Continuously Tunable Erbium-Doped Fibre Laser Using Tunable Fibre Bragg Gratings and Optical Circulator

A continuously tunable erbium-doped fibre laser （TEDFL） based on tunable fibre Bragger grating （TFBG） and a three-port optical circulator （OC） is proposed and demonstrated. The OC acts as a 100%-reflective mirror. A strain-induced uniform fibre Bragger grating （FBG） which functions as a partial-reflecting mirror is implemented in the linear cavity. By applying axial strain onto the TFBG, a continuously tunable lazing output can be realized. The wavelength tuning range covers approximately 7.00nm in C band （from 1543.6161 to 1550.3307nm）. The side mode suppression ratio （SMSR） is better than 50 dB, and the 3 dB bandwidth of the laser is less than 0.01 nm. Moreover, an array waveguide grating （AWG） is inserted into the cavity for wavelength preselecting, and a 50 km transmission experiment was performed using our TEDFL at a 10 Gb/s modulation rate.     

1 μm wavelength swept fiber laser based on dispersion-tuning technique

We report a wavelength swept fiber laser at the 1 μm region based on an actively mode-locked dispersion-tuning technique. The ring-cavity laser uses a 70 cm ytterbium-doped fiber as a gain medium. Mode locking is achieved by the direct modulation of the amplitude modulator, and a ～1000 m single-mode fiber is used to provide the desired intracavity dispersion. By sine-modulating the modulation frequency, a wavelength swept laser with a range of ～30 nm can be achieved at a sweeping rate of 50 Hz. The characteristics of the laser, such as its singlewavelength tuning range, tuning sensitivity, static linewidth and sweeping rate, are also studied experimentally.     

Cost-effective tunable fiber laser based on self-seeded Fabry-Perot laser diode using a Sagnac loop reflector

We propose and demonstrate a simple configuration of wavelength-tunable fiber laser made up of a tunable band-pass filter, a Sagnac loop refiector, and a Fabry-Perot laser diode. Based on the self-seeded operation, the proposed fiber laser can obtain a single-longitudinal-mode output in the wavelength tuning range of 1544.69–1563.39 nm with tuning step of 1.34 nm. The performances of output power （-9 dBm）, optical side-mode suppression ratio （ 65.5 dB）, and power and wavelength stabilities are well exhibited.     

Broadband Brillouin slow light with multiple-longitudinal-mode,tunable pump

We propose and demonstrate broadband Brillouin slow light using a multiple-longitudinal-mode tunable fiber laser as Brillouin pump. A tunable broadband Brillouin pump with a tuning range from 1 520 to 1 555 nm is generated using a fiber ring laser with a semiconductor optical amplifier (SOA) as its gain medium. The pump spectrum consists of a large number of longitudinal modes separated by 6 MHz. The 3-dB bandwidth is about 11.5 GHz, and its fluctuation is less than 100 MHz within the tuning range. An 8-Gb/s data signal can be delayed by up to 83.0 ps (bit error rate < 10 9) at 17-dBm pump power.     

Widely Tunable Two-Section Directly Modulated DBR Lasers for TWDM-PON System

Wavelength tunable and directly modulated distributed Bragg reflector(DBR)lasers with butt-joint technology are designed,fabricated and characterized.The DBR laser consists of a gain section and a DBR section.To increase the electrical isolation between the gain section and the DBR section,parts of a p-doped material in the isolation region are etched off selectively.Over 2 kΩ isolation resistance is realized ultimately without the need of ion implantation,which simplifies the fabrication process.The laser exhibits high speed modulation with a large tunable range.The 3 dB direct modulation bandwidth of the device is over 8 GHz in a 12 nm tunable range.This widely tunable DBR laser with the simple structure is promising as a colorless light source for the next-generation time and wavelength division multiplexed passive optical network(TWDM-PON)systems.     

Dual-wavelength distributed Bragg reflector semiconductor laser based on a composite resonant cavity

We report a monolithic integrated dual-wavelength laser diode based on a distributed Bragg reflector (DBR) composite resonant cavity. The device consists of three sections, a DBR grating section, a passive phase section, and an active gain section. The gain section facet is cleaved to work as a laser cavity mirror. The other laser mirror is the DBR grating, which also functions as a wavelength filter and can control the number of wavelengths involved in the laser action. The reflection bandwidth of the DBR grating is fabricated to have an appropriate value to make the device work at the dual-wavelength lasing state. We adopt the quantum well intermixing (QWI) technique to provide low-absorption loss grating and passive phase section in the fabrication process. By tuning the injection currents on the DBR and the gain sections, the device can generate 0.596 nm-spaced dual-wavelength lasing at room temperature.     

Efficient Long Wave IR Laser from Ho：YAG 2 μm Pumped ZnGeP2 Optical Parametric Oscillator

An efficient high power long wave infrared laser based on ZnGeP2 optical parametric oscillator pumped by a 2.09μm Tm：YLF/Ho：YAG laser at 10KHz pulse repetition rate is reported. The pump to idler conversion efficiency is 8% at 15.6W Ho pump power level and a quantum efficiency of 31% when the 1idler wavelength is tuned at 8.08μm. The wavelength tuning range from 8-9.1μm is also achieved by rotating the ZGP crystal.     

A grating-coupled external cavity InAs/InP quantum dot laser with 85-nm tuning range

The optical performance of a grating-coupled external Continuous tuning from 1391 nm to 1468 nm is realized at cavity laser based on InAs/InP quantum dots is investigated. an injection current of 1900 mA. With the injection current increasing to 2300 mA, the tuning is blue shifted to some extent to the range from 1383 nm to 1461 nm. By combining the effect of the injection current with the grating tuning, the total tuning bandwidth of the external cavity quantum-dot laser can reach up to 85 nm. The dependence of the threshold current on the tuning wavelength is also presented.     

Mid—Infrared Optical Parametric Oscillator Based on All—Solid—State—Pumped Periodically Poled LiNbO

We report the tunable mid-infrared generation with a periodically poled LinbO3(PPLN).Using an all-solid-state pumped Nd:YVO4 laser as the pump source and a PPLN nonlinear crystal with grating periods of 28.2-30.8μm,we have achieved wavelength conversion in the 2.90-4.05μm spectral range by period tuning.The use of confocal cavity design has brought a compact,all-solid-state configuration with an average output powers of idler up to -200mW.The maximum power of 277mW was obtained at the wavelength of 3.35um.     

Fabrication of widely tunable ridge waveguide DBR lasers for WDM-PON

We report the fabrication of widely tunable ridge waveguide distributed Bragg reflector(DBR) lasers with InGaAsP butt-joint as grating material. The shape of the butt–joint interface is found to have significant effect on the properties of the lasers. It is shown that irregular mode jumps during wavelength tuning can be avoided by a V-shaped butt–joint interface. From the fabricated device, 23 channels with 0.8 nm spacing and greater than 35 dB side mode suppression ratios are obtained. The different tuning characteristics of the ridge waveguide and the previously reported buried ridge stripe DBR lasers are discussed. Combined with the wide tuning range and the simple structure, the ridge waveguide DBR lasers are promising for use in wavelength division multiplexing passive optical networks(WDM-PONs).     

Novel discretely tunable narrow linewidth fiber laser with uniform wavelength spacing

A novel configuration of the tunable fiber laser with uniform wavelength spacing in dense wavelength division multiplexing (DWDM) application is proposed.The ring type tunable fiber laser consists of an all-fiber comb filter which determines the wavelength spacing,and a piece of adjustable fiber grating to select the discrete lasing wavelength for DWDM application.The proposed all-fiber ring type tunable laser has potential application in the DWDM and other optical systems due to its advantages such as narrow linewidth,easy tuning,uniform wavelength interval,etc..     

Distributed Bragg reflector laser(1.8 μm) with 10 nm wavelength tuning range

We report a 1.8 μm two-section distributed Bragg reflector laser using butt-jointed In Ga As P bulk material as the waveguide core layer. The threshold current is 17 m A and the output power is 8 m W on average. The threshold current, output power, and emitting wavelength dependences on temperature are measured. The obtained wavelength tuning range is 10 nm. This device has potential applications in simultaneous multiple-gas detection.     

Fifty-five km reach,bidirectional, 400 Gb/s(40×10 Gb/s), channel-reuse DWDM–PON employing a self-wavelength managed tunable laser

We experimentally demonstrate a channel-reuse bidirectional 10 Gb∕s∕λ long-reach dense wavelength-division multiplexing passive optical network(DWDM-PON) and an optical beat-noise-based automatic wavelength control method for a tunable laser used in a colorless optical network unit(where λ· wavelength). A55 km, bidirectional, 400 Gb/s(40 × 10 Gb∕s) capacity channel-reuse transmission with 100 GHz channel spacing is achieved. The transmission performance is also measured with different optical signal to Rayleigh backscattering noise ratios and different central wavelength shifts between upstream and downstream in the channel-reuse system.     

High-power and wavelength tunable diode-pumped continuous wave Yb:SSO laser

A wavelength-tunable,efficient,and high-average power single diode-pumped continuons wave(CW) Yb:SSO laser is reported.A maximum output power of 8.8 W at 1 062.6 nm is obtained using the absorbed pump power of 11.7 W,which corresponds to a slope efficiency of 85.5% and an optical-to-optical conversion efficiency of 48.9%.The wavelength tuning of the Yb:SSO laser pumped by the 976-nm LD is also investigated.The results show the tuning range from 1 002.30 to 1 068.47 nm,which corresponds to a tunability range of 66.17 nm.