Optical Gain at 637 nm Wavelength in Polymer Waveguide Amplifier Under Commercial LED Pumping for Planar Photonic Integration

Abstract

transmit data [1] and has attracted considerable interest in optical local area networks and photonic integrated circuits. Plastic optical fibers (POF) are typically employed to transmit optical signals in VLC systems. [2,3] Although POF have low absorption losses in the visible wavelength window, it is still necessary to use optical waveguide amplifiers to compensate for the propagation loss. Moreover, there is a growing demand for chip-level monolithic photonic systems that integrate optical devices with various functions, such as optical multiplexing, switching, modulation, and amplification. These systems should employ waveguide amplifiers operating across the visible and near-infrared spectral ranges to compensate for the optical losses.Owing to their low absorption loss, simple processing, and being low cost, optical waveguide amplifiers based on polymer materials exhibit great potential in the visible wavelength region in photonic integrated circuits. For optical amplification in the red region, ongoing research mainly focused on the organic dyedoped [4][5][6] and rare-earth Eu 3+ ions or Er 3+ ion-doped polymer waveguide amplifiers. [7][8][9][10] The organic dye-doped optical amplifier pumped with a 575 nm pulsed laser achieved a relative gain of 9.3 dB cm −1 at 650 nm in a waveguide with a cross-section of 7 µm × 100 µm. [11] The rare-earth Eu 3+ ions-doped waveguide amplifier pumped with a 351 nm laser showed a gain of 8.6 dB cm −1 at 612 nm with a cross-section of 2.7 µm × 100 µm. [7] For Er 3+ ion-doped polymer amplifiers, a relative optical gain of 2.0 dB cm −1 at 650 nm, based on the up-conversion of Er 3+ ions, was obtained upon the excitation of a 976 nm laser diode (LD). [9] In addition to the waveguide amplifiers mentioned above, almost all waveguide amplifiers, such as Er 3+ -doped inorganic materials, [12][13][14] Nd 3+ -doped polymer [15][16][17] frequently select LDs as pump sources. In the pumping mode, either light-beam spatial coupling [7,10,17] or a wavelength division multiplexer (WDM) [12,18,19] is generally used to combine the signal laser with a pump laser. The light beam spatial coupling possess the disadvantage of limiting the amplifier to a 1D axial space, as shown in Figure 1a, which is not conducive to the application of Optical gains at 637 nm wavelength using light-emitting diodes (LEDs) instead of traditional semiconductor lasers as pumping sources are demonstrated in the organic molecule 2,6-bis[4-(diphenylamino)phenyl]-9,10-anthracenedione (AQ(PhDPA) 2 )-doped polymethylmethacrylate (PMMA) and SU-8 polymer waveguides. Under excitation of four blue-violet LEDs with different central wavelengths, fluorescence in the red band is observed owing to the transition of AQ(PhDPA) 2 from the excited states to the ground state based on the thermally activated delayed fluorescence (TADF) mechanism. Channel waveguides with a cross-section of 6 µm × 5 µm are fabricated. The relative gains of 5.0 and 4.0 dB cm −1 are obtained in rectangular waveguides with active core layers as AQ(PhDPA) ...

Optical Amplification at 637 and 1067 nm Based on Organic Molecule AQ(PhDPA)2 and NdIII Complex Codoped Polymer Waveguides

“…This is mainly due to the decreasing doping content of organic molecule AQ (PhDPA) 2 in the codoping system. However, compared with the gain of 2.6 dB cm −1 in 0.5 wt% AQ(PhDPA) 2 -doped PMMA waveguide in our previous work, [20] the gain of 4.9 dB cm −1 has almost doubled although the doping concentration of AQ(PhDPA) 2 decreased to 0.325 wt% in AQ(PhDPA) 2 -FDPO codoped PMMA at the mass ratio of 1:4, as shown in Figure 9d, which is consistent with the PL spectra. This also proves that the effective energy transfer path has been established between the ligands and AQ (PhDPA) 2 in the codoped system.…”

“…[29] A more detailed discussion on the TADF mechanism can be found in our previous study. [20] The emissions of Nd 3+ ions at 1067 nm with FWHM of 27 and 24 nm were also obtained in 1 wt% Nd(DBTTA) 3 (DBFDPO) and Nd(DBTTA) 3 (FDPO)-doped PMMA films, respectively, corresponding to the transition of Nd 3+ ions from the 4 F 3/2 to 4 I 11/2 state, as demonstrated by the purple and light-purple solid lines. The emission intensity of Nd(DBTTA) 3 (DBFDPO) was slightly stronger than that of Nd(DBTTA) 3 (FDPO) because the ligand DBFDPO has a stronger rigid structure that prevents the solvent from entering the complex; thus, weakening the solvent effect on the luminescence efficiency of the complex.…”

“…In recent years, the majority of the previous researches conducted on polymer waveguide amplifiers reported the values of relative gain less than 5.0 and 4.0 dB cm −1 at 0.6 µm and 1.06 µm respectively, as indicated in Figure 11. [1,20,[37][38][39][40][41][42][43][44][45][46][47] Moreover, these polymer waveguide amplifiers all focus on the optical amplification at a single wavelength. Based on AQ(PhDPA) 2 -FDPO (1:4) in this work, the relative gain value of 6.1 dB cm −1 at 637 nm obtained in waveguides with crosssection of 4 × 8 µm 2 is at an advanced level compared with the gains achieved in larger size of waveguides reported so far; in addition, the gain of AQ(PhDPA) 2 -DBFDPO (1:4) of 4.8 dB cm −1 is also a pretty good gain performance at 0.6 µm.…”

“…An optical gain of 2.6 dB cm −1 at 637 nm with pumping of a 450 nm LED has been demonstrated in TADF AQ(PhDPA) 2 doped polymer waveguide in our previous work. [20] Therefore, it is meaningful to study the optical properties of rare-earth complexes and TADF molecules AQ(PhDPA) 2 -codoped polymer under the excitation of LEDs. The research of the fluorescence changes caused by the energy transfer between the two emission centers has broad application prospects for improving the optical gain of single wavelength or the synchronous amplification of dual wavelengths in dense wavelength division multiplexing (DWDM) systems.…”

On-Chip Ultralow-Threshold Tunable CdSSe Nanobelt Lasers Excited by the Emission of Linked ZnO Nanowire

“…In recent years, a low-threshold nanolaser source is highly desirable for on-chip nanophotonics. − Miniaturization of photonic devices is still in the rudimentary stage, and for nanolasers, high antidamage ability and stability are also imperative. − For this reason, the integration of nanolasers has attracted great interest in the photonics community. , With the development of semiconductor materials and with rich optical behaviors at micronano scale being found gradually, many micronano photonic devices with various functions have been realized. − …”