FIG 1 - uploaded by Shigeki Takeuchi
Content may be subject to copyright.
Schematic of experimental setup. VOA: variable optical attenuator, FC: 95/ 5 fused fiber coupler, PM: optical power meter, and WDM: 980/ 1550 nm wavelength division multiplexer.
Source publication
Lasing of a taper-microsphere system with a gain layer of submicrometer thickness is demonstrated. For the gain layer, an Er3+-doped P2O5-Al2O3-SiO2 thin film with a thickness of 200 nm was fabricated using the sol-gel method on a silica microsphere. The demonstration of single-mode lasing with the thin gain layer suggests the improved dispersion o...
Similar publications
The sol-gel process was employed in the preparation of titania-doped spherical nanosilica for application in photocatalysis. To this end, the silica matrix was doped with 1 and 10% titania, and the catalytic activity of the resulting solids in the degradation of rhodamine was tested. The synthesized materials were thermally treated at 120, 400, and...
Citations
... The high optical gain was favor to reduce the required length of the gain materials, then reduce the nonlinear effects when applied in high power lasers and simplify the construct of the optical amplifiers and lasers. Among various host glasses, silica was most widely used in optical amplifiers and fiber lasers due to its excellent mechanical and chemical properties [12][13][14]. However, high doping concentration will deduce the phase separation between the rare earth ion and silicon dioxide. ...
Constructing the glass matrix to avoid the concentration quenching is significant to obtain heavily doping and higher optical gain glasses. In this work, B2O3-Na2O binary glasses with different O/B were employed for discussing the relationship between the glass structure and erbium ions concentration quenching. The Raman spectra indicated that when the O/B was 0.16, the [BO3] would be mostly transformed into [BO4] in the glass network, and furtherly increased O/B, the [BO3] would not be transformed into [BO4] continuously. The critical doping concentration was highest when the O/B was 0.16, which suggested that the relative complete framework structure would be beneficial to obtain homogenously distribution of rare earth ions. Lower O/B, more diverse of the glass structure units, which would be favor to obtain broadband width of NIR fluorescence of Er³⁺ ions.
... Since the resonance mode in a high Q-value (>10 6 ) cavity has a sub-pico-meter full width at half maximum (FWHM) in its spectrum, it could be used as a feedback device in the laser cavity for narrowing the laser linewidth and stabilizing the laser frequency. Several types of WGM microcavities including CaF2 [13][14][15][16] and MgF2 [17][18][19][20] disks, LiNbO3 resonator [21], silica microsphere [22][23][24] and microcylinder [25], and rare earth doped microsphere [26,27] have been successfully exploited to achieve the frequency stabilized lasers. In general, the output wavelength of the fiber laser basing on the above solid-core WGM microcavity is relied on controlling the relative position between the fiber taper and the microcavity [22,25]. ...
The laser frequency of an Er-doped fiber ring cavity is stabilized using the microbubble resonator (MBR) as the feedback element. The linewidth of the laser is nearly 86 MHz at ~ 1560 nm measured by the Fabry-Perot interferometer. Since the thermo-optic effect changes the reflectivity of the modes excited inside the MBR, the transition from the dual-wavelength operation to a stable single-wavelength output is found as increasing the pump power. The outstanding advantage of such laser is the microfluidic channel of the MBR which provides an excellent platform for the light to interact with the liquids. Thus, the laser wavelengths could be tuned by injecting different refractive index (RI) liquids into the microbubble. A coupled-cavities system is setup through inserting the MBR into the fiber cavity directly, of which the laser spectrum is very sensitive to the light polarization. Moreover, the laser wavelength could be tuned in a wide wavelength range if the thin wall MBR is adopted. It provides a way to realize different lasing statues by controlling the light polarization or the RI of liquids inside the MBR.
... Since the pioneering works of Garret et al. [13] on Sm 2 þ :CaF 2 spheres and works on Morphology-Dependent Resonances (MDRs) and laser effects in droplets during the 80's [4] rare earth-doped glass microspherical lasers became subject of numerous studies, significant progress was achieved in the past decade as described in recent reviews [14,15]. Up to now, WGM microspherical lasers have been obtained by melting rare-earth doped optical fiber tips using fusion techniques [11,[16][17][18], by microwave plasma torch fusion of grounded powers [19,9] or by electric tube furnace [20] by sol-gel [21][22][23] or glass [24] coating of silica microspheres and by rare-earth ion implantation [25]. The literature about WGM microresonators (WGMR) laser is vast and deep; there are many papers based on WGMR with different geometrical shapes (microspheres, microdisks, toroids, etc.), made of various glasses (silica, telluride, phosphate, ZBLAN, etc.) and various dopants (Er, Er:Yb, Nd, Tm, Er:Yb:Tm, etc.), which cannot be all cited here but have been described in several reviews [14,26] and specially in [15]. ...
We report experimental results regarding the development of Er3+-doped glass microspherical cavities for the fabrication of compact sources at 1.55 μm. We investigate several different approaches in order to fabricate the microspheres including direct melting of Er3+-doped glass powders, synthesis of Er3+-doped monolithic microspheres by drawing Er3+-doped glass, and coating of silica microspheres with an Er3+-doped sol–gel layer. Details of the different fabrication processes are presented together with the photoluminescence characterization in free space configuration of the microspheres and of the glass precursor. We have analyzed the photoluminescence spectra of the whispering gallery modes of the microspheres excited using evanescent coupling and we demonstrate tunable laser action in a wide range of wavelengths around 1.55 μm. As much as 90 μW of laser output power was measured in Er3+-doped glass microspheres.
... The origin of the distance between the tapered fiber and the tip was determined as the position where the tip was contacted to the surface of the tapered fiber. These components and samples were placed in a plastic box to keep a stable condition [30]. The transmitted light from the end of the tapered fiber was measured using a highly sensitive photodiode (Thorlabs, DET36A) and a digital oscilloscope (Tektronix, TDS5034). ...
... A tapered fiber (diameter: 200 ~1000 nm) was fabricated by heating a fused-silica singlemode optical fiber (Thorlabs, 780HP) with a ceramic heater and at the same time stretching both ends of the fiber [30,31]. We monitored the transmittance in the tapered fibers at wavelength about 780 nm during the fabrication process. ...
A simple tapered fiber based photonic-plasmonic hybrid nanostructure composed of a thin tapered fiber and a pseudoisocyanine (PIC)-attached Au-coated tip was demonstrated. Using this simple hybrid nanostructure, we succeeded in observing two-photon excited fluorescence from the PIC dye molecules under a weak continuous wave excitation condition. From the results of the tip-fiber distance dependence and excitation polarization dependence, we found that using a thin tapered fiber and an Au-coated tip realized efficient coupling of the incident light (~95%) and LSP excitation at the Au-coated tip, suggesting the possibility of efficiently inducing two-photon excited fluorescence from the PIC dye molecules attached on the Au-coated tip. This simple photonic-plasmonic hybrid system is one of the promising tools for single photon sources, highly efficient plasmonic sensors, and integrated nonlinear plasmonic devices.
... Among them, silica microsphere cavities formed by surface tension have been shown with extremely high optical quality factors of ∼10 10 , due to their ultra-low material absorption and nearly atomicscale surface roughness [3,4]. When incorporated with active gain media such as rare-earth ions [5][6][7][8][9][10][11][12][13], dyes [14], semiconductors [15] or nanocrystal quantum dots [16,17], WGM optical microcavities can be used for low-threshold microlasers and microlaser-based label-free sensors [18]. So far, typical spherical microlasers have been obtained by directly heating rare-earth-doped optical fiber tips using a CO 2 laser [6][7][8] or by doping pure silica microspheres by coating rare-earth-doped sol-gel films [9,13] or by using rareearth ion implantation [12], all of which have been realized with different lasing wavelengths [19]. ...
... When incorporated with active gain media such as rare-earth ions [5][6][7][8][9][10][11][12][13], dyes [14], semiconductors [15] or nanocrystal quantum dots [16,17], WGM optical microcavities can be used for low-threshold microlasers and microlaser-based label-free sensors [18]. So far, typical spherical microlasers have been obtained by directly heating rare-earth-doped optical fiber tips using a CO 2 laser [6][7][8] or by doping pure silica microspheres by coating rare-earth-doped sol-gel films [9,13] or by using rareearth ion implantation [12], all of which have been realized with different lasing wavelengths [19]. Recently, silica optical microsphere cavities fabricated on a silicon chip have been realized and used for cavity optomechanics [20][21][22]. ...
We demonstrate a low-threshold microsphere laser on a silicon chip, fabricated from erbium-doped silica sol–gel film. Single-longitudinal mode lasing emission is observed from a 37 μm diameter microsphere cavity with an erbium ion concentration of 2 × 1019 cm−3. The measured lasing threshold of the silica microsphere laser is as low as 4.8 μW.
... Initial results with glass spheres indicated that Q values in excess of 10 9 were possible [10]. Gain materials can be incorporated into a solid resonator by various approaches, such as directly fabricating the resonator from an active medium doped material [38][39][40], coating the resonator with light emitters [41][42][43][44][45][46], and doping the resonator with gain materials by ion implantation [47]. In [38], laser REVIEW ARTICLE 63 Figure 4 (online color at: www.lpr-journal.org) ...
Whispering gallery mode (WGM) optical microresonators have attracted intense interests in the past decades. The combination of high quality factors (Q) and small mode volumes of modes in WGM resonators significantly enhances the light-matter interactions, making them excellent cavities for achieving low threshold and narrow linewidth lasers. In this Review, the progress in WGM microcavity lasers is summarized, and the laser performance considering resonator geometries and materials as well as lasing mechanisms is discussed. Label-free detection using WGM resonators has emerged as highly sensitive detection schemes. However, the resolution is mainly limited by the cavity Q factor which determines the mode linewidth. Microcavity lasers, due to their narrow laser spectral width, could greatly improve the detection resolution. Some recent developments in sensing using microcavity lasers are discussed.
... Input-output efficiencies of nearly 100% are possible [2,3]. Such fiber-coupled microspheres have application in various optical devices, such as low-threshold lasers45678, biochemical sensors [9], and nonlinear optical devices [10,11] . These systems have also attracted interest for solidstate devices using cavity quantum electrodynamics (CQED) for photonic quantum information technology. ...
The coupling of a microsphere resonator to a tapered fiber was demonstrated at cryogenic temperatures (8 - 13 K) and investigated with a probe laser light whose frequency around the zero phonon line of nitrogen vacancy centers in diamond (638 nm). For this purpose, a liquid-helium-flow cryostat with a large sample chamber is developed and a resonance dip with a Q of 2 x 10(6) is observed. The resonance frequency and the coupling condition are found to be stable for a period of one hour. (C) 2010 Optical Society of America
... To achieve zero-or low-threshold microlaser, luminescence medium should be coupled into the microspheres to obtain certain gain. Some interesting techniques have been reported for observing lasing action in microspheres, such as fabricating microspheres with Nd -doped fiber [3] or Er : Yb-codoped phosphate [8]- [10] or Er [11] (or Tm [12]) doped tellurite glass, coating purely passive microspheres with sol-gel silica glass layer [13]- [16] or CdSe-ZnS nanocrystals [17] or HgTe [18] quantum dots, immersing silica microsphere in dye solution [19], and implanting single Er ions with an ion accelerator [20]. The presence of luminescence materials usually decreases the quality factor of WGMs, and the threshold of the microlaser increases obviously. ...
We developed a new method to fabricate a silica microsphere coated by a thin layer of Er : Yb-doped phosphate glass. The coated microsphere possessed high- Q whispering-gallery modes and formed single-mode and multimode microlasers in the both 1550- and 1040-nm bands. A low-loss fiber taper was used to not only launch the pump power around 980 nm into the microsphere, but also collect the resulting laser emissions. In our experiment, the threshold pump power as low as 30 muW of a single longitudinal mode was obtained.
