Multi-wavelength Laser Research Articles

Thermal analysis and package optimization for the multi-wavelength laser bar module

To meet the demand of the laser application market for semiconductor laser function diversification, this paper proposes a handheld multi-wavelength laser stack packaging module. The 808 nm, 915 nm, and 980 nm semiconductor laser bars are selected for the integrated assembly of the multi-wavelength module. However, with the continuous increase of the optical power density of the integrated packaging module, thermal management has become a key factor affecting the performance and life of the device. In this paper, the finite element analysis method is used to analyze the influence of the arrangement of three laser stripe chips in the stacked packaging structure on the heat dissipation of the multi-wavelength module. The simulation results show that the heat dissipation efficiency of the multi-wavelength module can be improved by 13.74 % by changing the arrangement of chips. A back heat dissipation packaging structure with higher heat dissipation efficiency is proposed, and the influence of chip arrangement and working mode on the thermal characteristics of the device in the new packaging structure is simulated and analyzed. According to the simulation results, a chip arrangement that can make the heat dissipation effect of the multi-wavelength module achieve the best is determined.

An Energy-Efficient and Bandwidth-Scalable DWDM Heterogeneous Silicon Photonics Integration Platform

Heterogeneous III-V-on-silicon photonic integration has proved to be an attractive and volume manufacturable solution that marries the merits of III-V compounds and silicon technology for various photonic integrated circuit (PIC) applications. The current main-stream Ethernet trends for larger bandwidth are pushing higher modulation baudrate or employing advanced modulation format for datacom applications. However, neither solution is likely able to significantly drive overall solution cost and energy efficiency to the best sweet spot, nor to unfold the full potential of heterogeneous integration. Here we review our innovations on a special heterogeneous III-V-on-silicon platform, and the development of a dense wavelength division multiplexed (DWDM) transceiver. A 40-channel DWDM architecture and platform fabrication are discussed first, followed by experimental demonstration of each high-quality building block. InAs/GaAs quantum dot material is the choice for building robust multi-wavelength lasers, amplifiers, and high-speed avalanche photodetectors (APDs) which complements the more mature SiGe APDs. A metal-oxide-semiconductor capacitor phase shifter is a mission critical structure to provide athermal and efficient tuning for deinterleavers and microring resonators, and high-speed modulation. A successful 8 × 25 Gb/s link demonstration paves the way for the world's first fully-integrated DWDM PIC on Si with Terabit/s aggregated bandwidth and energy efficiency likely to ∼100 fJ/bit.

Switchable multi-wavelength fiber laser based on a taper-coupled microbottle resonator

A multi-wavelength erbium-doped fiber laser (EDFL) based on a taper-coupled microbottle resonator is proposed and investigated experimentally. The taper-coupled microbottle resonator has the comb filter characteristics with Q factor 2.9 × 104, which is integrated into an EDFL system. The taper-coupled microbottle resonator was packaged by ultraviolet glue, which has excellent stability of output power and wavelength at room temperature. Then, switchable dual-, triple-, quad- and quint-wavelength fiber laser states can be achieved by adjusting the polarization controller (PC). Furthermore, for dual-wavelength and triple-wavelength laser state, the position of output wavelengths also can be precisely modulated with the PC. The developed multi-wavelength EDFL has the optical signal to noise ratio as high as 40 dBm, and the wavelength shift and peak power fluctuation are less than 0.03 nm and 6 dBm.

Tunable all fiber multi-wavelength mode-locked laser with a large dynamic range using polarization controller coiled SMF-GIMF-SMF structure as both saturable absorber and comb filter

We have demonstrated a tunable, multi-wavelength mode-locked fiber laser with a large dynamic range based on polarization controller (PC) coiled graded index multimode fiber (GIMF) as a saturable absorber (SA) and comb filter for the first time. The SA device that consists of a section of GIMF coiled into a polarization controller and two sections of single mode fibers aim to mitigate the technical difficulty of multimode fiber (MMF) in the length accuracy requirements and tune multi-wavelength operation in an Yb-doped fiber laser. Nonlinear multimode interference and transverse light field evolution in multimode fiber are simulated. Experimentally, we achieved the stable continuous-wave mode-locked (CWML), pulse bunches, and high-harmonic mode-locked (HML) operation. Furthermore, the PC-based GIMF structure can also be used as a filter to tune the laser line numbers. Continuously tunable multi-wavelength mode-locked operation with a large dynamic range was demonstrated by varying the polarization orientation of MMF. The range of six-wavelength spectrum is up to 28 nm. Our results indicate that the PC coiled GIMF could serve as an SA and a filter, which makes it beneficial to realize tunable, multi-wavelength mode-locked laser with a large dynamic range.

Switchable and tunable multi-wavelength erbium-doped fiber ring laser based on single STS filter

A novel switchable and tunable multi-wavelength erbium-doped fiber ring laser (EDFL) is proposed and experimentally demonstrated by using a single SMF-TMF-SMF (STS) structure filter. The STS filter, based on mode interference, is fabricated by sandwiching a section of two-mode fiber (TMF) between single mode fibers (SMF) through core-offset splicing, which has a comb spectrum with obvious envelope and uniform fluctuation. The transmission characteristics of the STS filter can be changed by adjusting the polarization controller (PC) wrapped on the TMF. Based on the cooperation of the STS filter and polarization dependent loss (PDL), the fiber laser can be individually switchable and widely tunable. By adjusting the PC, the outputs can be switched from single-wavelength to adjacent eight-wavelength and can be tuned in the range of 1528 ∼ 1561 nm. Furthermore, non-adjacent dual-, three- and four-wavelength with different intervals can also be achieved by appropriately adjusting the PC. With the assistance of four wave mixing (FWM) effect, the fiber laser has a stable output. The tuning and switching of the proposed multi-wavelength EDFL is simple and flexible.

Multi-wavelength random fiber laser based on a tilted parallel inscribed apodized fiber Bragg grating array.

We propose and demonstrate a multi-wavelength random fiber laser (RFL) based on a novel, to the best of our knowledge, compact apodized fiber Bragg grating array (AFBGA). The AFBGA is fabricated by a femtosecond laser with the point-by-point tilted parallel inscription method. The characteristics of the AFBGA can be flexibly controlled in the inscription process. Hybrid erbium-Raman gain is used in the RFL and reduces the lasing threshold to sub-watt level. Stable emissions at two to six wavelengths are achieved with the corresponding AFBGAs, and more wavelengths are expected with higher pump power and AFBGAs containing more channels. A thermo-electric cooler is employed to improve the stability of the RFL, and the maximum wavelength and power fluctuations of a three-wavelength RFL are 64 pm and 0.35 dB, respectively. With flexible AFBGA fabrication and simple structure, the proposed RFL enriches the choice of multi-wavelength devices and has significant potential in practical applications.

Comparison of back conversion and power differential in extra-cavity multi-optical parametric oscillator using MgO:APLN

The extra-cavity multi-optical parametric oscillator (MOPO) using MgO-doped aperiodically poled lithium niobite (MgO:APLN) is a technique to generate multi-wavelength tunable laser output, in which the back conversion and power differential can reduce the output power and conversion efficiency. A comparison of the back conversion and power differential between the two methods is presented in this paper. One approach is to adjust the mirror transmittance to change the parametric light's power density involved in the oscillation. With 1.47 μm transmittance of 20 % and 3.30 μm transmittance of 60 %, the 3.30 μm output power is 0.95 W, the 3.84 μm output power is 0.94 W, and the power ratio is 1.01. The other approach is to add two electro-optical polarization mode converters (EO PC) to change the parametric light's polarization. When the electric fields of two EO PCs are 66 V/mm and 15 V/mm, the 3.30 μm and 3.84 μm output powers are 2.54 W and 2.49 W, the conversion efficiencies are 10.3 % and 10.0 %, and the power ratio is 1.02. The comparison results confirm that both methods have the capability of back conversion suppression and power differential reduction. Compared with the adjusting transmittance, adding EO PCs has higher output power and conversion efficiency, which is the first reported method for better balanced multi-wavelength laser output.

Tunable and Switchable Multi-Wavelength Erbium-Doped Fiber Laser Based on Composite Structure Filter

A multi-wavelength erbium-doped fiber laser (MW-EDFL) with wide tuning range, switching and adjustable wavelength interval is designed and tested, which is based on a composite filter. The filter consists of a tapered microfiber coupler loop (TMCL) with a nested single mode fiber (SMF)-two mode fiber (TMF)-SMF (STS) structure, which has a comb spectrum with obvious envelope and uniform fluctuation. Our experimental and theoretical results show that the laser can output thirteen wavelengths, when the angles of two polarization controllers (PCs) in the TMCL are accurately set. Moreover, by adjusting the PCs, the tuning range of single- to sextuple-wavelength can reach about 40 nm. Six non-adjacent multi-wavelength outputs can be observed in some specific polarization states. The maximum side-mode suppression ratio (SMSR) of the output laser is 40.6 dB. Compared with other multi-wavelength EDFL, the output characteristics of the laser, such as the adjustability and flexibility of wavelength spacing and the switch-ability of wavelength number, have been improved.

High-Stability multi-wavelength photonic crystal fiber laser based on nonlinear polarization rotation temperature measurement

We have proposed and experimentally demonstrated a multi-wavelength fiber laser with high-stability. The physical model and theoretical mechanism of nonlinear polarization rotation was theoretical analyzed. Here, we have developed a novel method with optimizing design for improving the laser stability for the multi-wavelength output based on Erbium doped photonic crystal fiber. By the experiments description, the output spectra of multi-wavelength was from 1558.34 nm to 1562.00 nm with 0.92 nm intervals, and the fluctuation of peak power was found to be less than 1 dB under 100 min operation scan at 20 ℃. More than that, the full temperature stability of the multi-wavelength outputs was tested with a pump power of a 980 nm LD of 278 mW and the temperature range of 25 ℃− 45 ℃, where the power fluctuation of 1559.64 nm, 1560.56 nm and 1561.48 nm laser outputs was less than 2.66 dB, 1.7 dB and 2.81 dB, respectively.

15.2: Design and Realization of Full‐Color VHG Holographic Waveguide Display

To realize the chromatic display function of VHG holographic waveguide display system, we firstly study the preparation process and holographic peformance of color‐sensitive acrylate based photopolymer. Based on the prepared photopolymer, we fabricated the RGB holographic waveguide device with the multiwavelength laser exposure method. Thus, for verifying the display function of the prepared device , the chromatic holographic waveguide near‐eye display module using the LCoS projector engine was developed. The application potential of the color‐sensitive photopolymer in holographic waveguide was also demonstrated.

Influence of multi-wavelength ultrafast laser texturing and autoclave sterilization on titanium alloy-based surface wettability

Titanium alloys are widely used in bio-medical applications for their excellent bio-compatibility and superior mechanical strength. On the other hand, femtosecond laser processing is a robust versatile and industrial method widely used for surface functionalization. In this work, laser-induced periodic surface structures (LIPSS) on titanium alloy (Ti6Al4V) using different laser wavelengths of 1030 nm (IR), 515 nm (Green) and 257 nm (UV) were created and their surface wettability (physical parameter correlated with cell adhesion) was studied, in relation to sterilization process. The contact angle over LIPSS was smaller than over polished samples, with Green and UV LIPSS presenting contact angles inferior to 20^circ and a superior stability to sterilization process.

Triple-wavelength laser from a femtosecond laser directly-written fiber cavity for microwave generation.

We report an all-fiber triple-wavelength single-frequency distributed Bragg reflector (DBR) laser for 1-10 GHz microwave (MW) generation. The DBR cavity contains a non-polarization-maintaining Er fiber and a pair of fiber Bragg gratings (FBGs) made using a femtosecond laser line-by-line (LbL) direct-writing method. Such a configuration combining a short cavity and radial asymmetry leads to frequency locking and phase controlling of multi-wavelength fiber lasers. A 1.59-µm triple-wavelength laser with high coherence, spectrum purity, and polarization purity has been demonstrated; 3-6 GHz triple-frequency MW was generated.

Energy-transfer controlled dual-wavelength visible laser generation based on parallel nonlinear frequency up-conversions

A compact frequency up-conversion scheme is demonstrated for dual-wavelength visible laser generation. The parallel sum-frequency generation (SFG) and second-harmonic generation (SHG) processes are simultaneously phase-matched and integrated in a well-designed periodically poled MgO:LiNbO3 crystal. Concurrent nonlinear up-conversions of the coupled SFG and SHG are thus realized. In the proof-of-principle experiment, two near-IR lasers at wavelengths of 800 nm and 1180 nm were used as independent fundamental beams. As a result, the generation of blue light at ∼477 nm by SFG (800 nm + 1180 nm → 477 nm) and the orange light at ∼590 nm by SHG of 1180 nm (1180 nm + 1180 nm → 590 nm) was simultaneously achieved. Finally, it is proved the relative strength of these two coupled nonlinear interactions and consequently the relative power of the blue and orange light could be freely controlled by changing the pump intensities of the fundamental beams, and a maximum photon conversion efficiency (∼25%) comparable to that of the separated SHG process was observed for this simultaneous dual-up-conversion device. This result provides a promising strategy for developing high-efficiency multi-wavelength visible laser systems. Combined with an engineered QPM crystal with different poling periods in sequence, more prospective nonlinear applications may be realized based a series of cascaded single- and dual-QPM nonlinear processes.

Switchable wide-band multi-wavelength fiber laser via Brillouin random lasing resonance

A switchable wide-band multi-wavelength Brillouin-erbium fiber laser constructed by a sub fiber loop (SFL) containing an erbium-doped fiber amplifier (EDFA) and a main fiber cavity (MFC) including a 1-km length of high nonlinear fiber (HNLF) via Brillouin random lasing resonance is proposed and experimentally investigated. The EDFA is incorporated into the sub fiber loop to boost optical power of the externally injected Brillouin pump (BP) light and Stokes wave fed back from the MFC, and the amplified BP light and Stokes wave are forward launched into the HNLF via the SFL, meanwhile, the generated Stokes wave is partially backward injected into the HNLF via the MFC, which make the Brillouin random lasing resonance of the Stokes wave form in the laser cavity. Using the proposed scheme, up to 19-orders backward-output Brillouin Stokes lines with a peak power discrepancy of less than 10 dB, and 281 stable forward-output Brillouin Stokes lines with a peak power discrepancy of less than 30 dB are obtained from the different output ports of the laser. Compared with the previous results, the backward generated Brillouin Stokes lines increase from 11 to 19 orders and the spectral-lines compositions also happen to change, and the forward generated stable Brillouin Stokes lines span over 30 nm and are extended by more than 18 nm. It is obvious that the generated Brillouin Stokes lines significant increasing should owe to the Brillouin random lasing resonance being introduced into the laser cavity. Influences of the system parameters including the BP power, EDFA pump power, and feedback power of Stokes wave on the laser lasing are investigated in detail. The proposed multi-wavelength fiber lasers can backward generate switchable Brillouin Stokes lines from 1st order to 19th order with an increasing wavelength number in turn, only by adjusting the EDFA pump power; moreover, the wavelength interval of the backward generated Brillouin Stokes lines can be switched between double- and single-Brillouin frequency shift, only by adjusting feedback power of the Stokes wave, without adding additional system configuration. A statistical analysis for the randomness of the multi-wavelength Brillouin-erbium fiber lasers is also done.

Mode-coupling effects in an optically-injected dual-wavelength laser.

Lasers designed to emit at multiple and controllable modes, or multi-wavelength lasers, have the potential to become key building blocks for future microwave photonic technologies. While many interesting schemes relying on optical injection have been proposed, the nonlinear mode coupling between different modes of a multi-wavelength laser and their dynamical behavior under optical injection remains vastly unexplored. Here, we experimentally and numerically study the effect of optical injection around the suppressed mode of a dual-wavelength laser and the resulting interactions with the dominant mode. We highlight a wavelength shift of the dominant mode triggered by injection locking of the suppressed mode and report a strong impact of the mode suppression ratio on the locking range. Finally, we show numerically that the cross-coupling parameter between the two modes might have a key role in this effect.

High-power multi-wavelength Yb-doped fiber laser with a tunable interval, amplitude, and a number of channels

In recent years, multi-wavelength lasers have attracted much attention due to their wide applications in various fields. In this Letter, we experimentally demonstrate a high-power multi-wavelength Yb-doped fiber laser with the aid of an acoustic-optic tunable filter, in which the wavelength interval, the intensity of each channel, and the number of lasing channels can be tuned independently. As a result, the operating wavelength tuning range covers 1040.0 to 1090.0 nm and the maximal output power reaches 15.7 W, which is higher than the previous reports by more than three orders of magnitude. The wavelength interval can be adjusted from 2.6 to 50 nm and the spectral profile can be arbitrarily controlled. Furthermore, the number of wavelength channels can be adjusted from 1 to 4. This work will provide a reference for achieving high-power spectral-flexible fiber sources.

A kind of multiwavelength erbium-doped fiber laser based on Lyot filter

A multiwavelength tunable ring-cavity erbium-doped fiber laser (EDFL) based on a Lyot filter was presented. For the proposed Lyot filter, a comb filter consisting of an EDF-polarization-maintaining fiber (EDF-PMF), a polarization controller (PC), and a circulator with four ports was used to suppress the mode competition. The light transmission direction was guaranteed by the circulator. For the proposed fiber laser, tunable single, dual, triple, quadruple, quintuple, sextuple, and septuple wavelengths were realized. A single-wavelength laser output with an optical signal-to-noise ratio (SNR) of up to 30.56 dB was realized, and a tuning range of 1590.54 nm to 1599.54 nm was achieved by tuning the PC. The stability of the single, dual, triple, and quadruple-wavelength center power fluctuations was less than 0.05 dB, 0.98 dB, 5.07 dB, and 7.71 dB respectively. When the laser was operated in the multiwavelength condition, the SNR was more than 20.97 dB. The proposed erbium-doped fiber laser is suitable for fiber-sensing system applications.

Tunable Brillouin-Raman multi-wavelength fiber laser with a linear cavity configuration

A tunable Brillouin-Raman multi-wavelength fiber laser has been proposed and demonstrated in a linear cavity configuration, where stimulated Raman scattering and stimulated Brillouin scattering occur simultaneously in the dispersion compensation fiber. The influence of Brillouin pump (BP) and Raman pump (RP) power on the obtained Brillouin Stokes lines has been investigated in detail. The experimental results show that when BP wavelength is 1545 nm, 63 orders of Stokes lines can be obtained at most, and the interval between adjacent lines is about 0.08 nm. Moreover, there are two opposite relations between the number of the generated Stokes lines and the BP power within the whole tunable range of 1520–1575 nm (55 nm), depending on the Raman gain. The proposed laser featuring simple structure will enable promising potentials in optical communications and optical sensor systems.

Design and analysis of polarization-beam-splitter-based fiber optical comb filter

In this paper, we proposed and demonstrated a novel switchable fiber comb filter based on polarization beam splitter (PBS). The proposed filter transmission characteristics is theoretically analyzed in detail by using the transmission matrix theory. The simulated results show that the filter can generate two different output channels selected by adjusting the polarization controllers (PC) in front of the PBS, and the two different channels’ wavelength intervals can be changed with polarization-maintaining fiber’s (PMF’s) characteristics. Different PMFs give a new switchable combination of channel intervals. A multi-wavelength fiber laser (MWFL) based on the proposed filter is experimentally demonstrated. Its wavelength interval can be switched among 0.85 nm, 0.40 nm, which is consistent with the simulated results of the filter. The power fluctuation of the two channel interval outputs in one hour is less than 0.88 dB and 1.37 dB, and the wavelength fluctuation is less than 0.06 nm and 0.18 nm, respectively.

Simple microwave photonic downconversion channelizer based on multi-wavelength laser sources.

This work presents a simple microwave photonic downconversion channelizer based on multi-wavelength laser sources. The design of two laser diode (LD) arrays enables signal multiplexing and simultaneous multichannel downconversion processing, which provide stable, relatively flat, and strong multi-frequency combs. A proof-of-concept experiment was taken, showing that 14.375-17.75 GHz broadband radio frequency (RF) signals were successfully downconverted to the same intermediate frequency (IF) and were sliced into four subchannels with 875 MHz bandwidth showing excellent image rejection and channel uniformity, which agrees with the simulation results. The spurious free dynamic range (SFDR) of the proposed RF channelizer is 100dBHz2/3, the image rejection is over 28 dB, and the frequency measurement error is less than ±6MHz. Replacing optical filters with electrical filters, the proposed simple optoelectronic hybrid reconfigurable microwave photonic channelizer system acquits stable performance and high maturity and meets the application requirements, behaving with stupendous potential in fields such as radar, satellite communication, electronic warfare, and others.