Extinction ratio and resonant wavelength tuning using three dimensions of silica microresonators

In this paper, a multidimensional tuning method of the silica microcapillary resonator(MCR) is proposed and demonstrated whereby the extinction ratio(ER) as well as the resonant wavelength can be individually controlled.An ER tuning range of up to 17 d B and a maximum tuning sensitivity of 0.3 d B/μm are realized due to the tapered profile of the silica optical microfiber(MF) when the MF is adjusted along its axial direction. Compared to direct tuning of the coupling gap, this method could lower the requirement for the resolution of displacement stage to micrometers. When the MF is adjusted along the axial direction of the silica microcapillary, a resonance shift of 3.06 nm and maximum tuning sensitivity of 0.01 nm/μm are achieved. This method avoids the use of an applied external field to control the silica microresonators. Moreover, when air is replaced by ethanol and water in the core of the silica microcapillary, a maximum resonance shift of 5.22 nm is also achieved to further enlarge the resonance tuning range. Finally, a microbubble resonator with a higher Q factor is also fabricated to achieve an ER tuning range of 8.5 d B. Our method fully takes advantage of the unique structure of the MCR to separately and easily tune its key parameters, and may broaden its applications in optical signal processing and sensing.

Wavelength Tuning in the Two-Section Distributed Bragg Reflector Laser Fabricatedby Quantum-Well Intermixing

The two-section tunable ridge waveguide distributed Bragg reflector (DBR) lasers fabricated by strained In xGa1-xAsyP1-y The threshold current of the laser is 51mA. The tunable range of the laser is 3.2nm and the side mode suppression ratio (SMSR) is more than 38dB.

Polarization control and tuning efficiency of tunable vertical-cavity surface-emitting laser with internal-cavity sub-wavelength grating

We design an 850 nm tunable vertical-cavity surface-emitting laser(VCSEL)structure using an internal-cavity sub-wavelength grating.The use of such a tuning structure allows for wider wavelength tuning range and more stable single-polarization as compared to conventional tunable VCSELs.The features of the internal-cavity grating effect on the wavelength tuning and polarization characteristics of the tunable VCSEL are analyzed.The simulation results show that the largest wavelength tuning range achieves 44.2 nm,and the maximum orthogonal polarization suppression ratio(OPSR)is 33.4 dB(TE-type)and 38.7 dB(TM-type).

Wavelength-tunable multi-point pump semiconductor disk laser based on an intra-cavity transmission grating

We report a wavelength-tunable multi-point pump scheme of the semiconductor disk lasers(SDLs).By designing an external cavity of SDL with an intra-cavity transmission grating,multiple pump gain regions share the same resonator.The effect of the intra-cavity grating on the output laser power,wavelength,and beam quality was investigated.The emission wavelength could be tuned over a bandwidth of~18 nm.With multi-point pumping,we achieve the laser output power with almost no loss,and further improvement is limited by the thermal effect.The changes in the beam are due to the mode selectivity by the intra-cavity grating.

Wavelength-tunable dissipative soliton from Yb-doped fiber laser with nonlinear amplifying loop mirror

We report a Yb-doped mode-locked fiber laser based on a nonlinear amplifying loop mirror[NALM],which is all-normaldispersion[ANDi],and allows the output wavelength to be tunable.The laser can generate a stable femtosecond dissipative soliton with a maximum output power of 196 mW.Its repetition rate is 112.4 MHz,and the final pulse duration is 236 fs.By adjusting the angle of the reflective diffraction grating,the mode-locked fiber laser was realized to tune the output with a tuning range of 54 nm from 1011.8 nm to 1065.6 nm.To the best of our knowledge,this is the widest tuning range of an ANDi Yb-doped mode-locked fiber laser based on NALM.

Study on Dual Bragg Wavelength Fiber Grating and Its Tuning Scheme

Because of package, a single FBG has dual Bragg wavelength. One is sensitive to stress and the other is sensitive to temperature. By using the special mechanism, the wavelengths can be tuned by stress and temperature respectively.

Wavelength calibration of narrowband ArF laser with iron hollow cathode lamp

Accurate and precise wavelength controlling of narrowband excimer lasers is essential for the lithography of an integrated circuit. High-precision wavelength tuning and calibration of a line-narrowed Ar F laser are presented in this work. The laser spectrum is narrowed to a sub-picometer with a line narrowing system. Absolute wavelength calibration of the line-narrowed laser is performed based on the optogalvanic（OG） effect using iron hollow cathode discharge（HCD）. An sccuracy of better than 0.1 pm for wavelength tuning and calibration is achieved with our homemade wavemeter.

Generation of 1.3/1.4μm random fiber laser by bismuth-doped phosphosilicate fiber

We have successfully generated a 1.3/1.4μm random fiber laser(RFL)using bismuth(Bi)-doped phosphosilicate fiber.The Bi-doped RFL has shown excellent long-term operational stability with a standard deviation of approximately 0.34%over 1 h at a maximum output power of 549.30 mW,with a slope efficiency of approximately 29.21%.The Bi-doped phosphosilicate fiber offers an emission spectrum ranging from 1.28 to 1.57μm,indicating that it can be tuned within this band.Here,we demonstrated a wavelength-tuning fiber laser with a wavelength of 1.3/1.4μm,achieved through the using of a fiber Bragg grating or a tunable filter.Compared to traditional laser sources,the RFL reduces the speckle contrast of images by 11.16%.Due to its high stability,compact size,and high efficiency,this RFL is highly promising for use in biomedical imaging,communication,and sensor applications.

Highly efficient tunable optical filter based on liquid crystal micro-ring resonator with large free spectral range

A highly efficient tunable optical filter of liquid crystal （LC） optical micro-r/rig resonator （MRR） was proposed. The 4-pro-radius ring consists of a silicon-on- insulator （SOI） asymmetric bent slot waveguide with a LC cladding. The geometry of the slot waveguide resulted in the strong electro-optic effect of the LC, and therefore induced an increase in effective refractive index by 0.0720 for the quasi-TE mode light in the slot-waveguide. The ultra-wide tuning range （56.0 nm） and large free spectral range （FSR） （-28.0nm） of the optical filters enabled wavelength reconfigurable multiplexing devices with a drive voltage of only 5 V. The influences of parameters, such as the slot width, total width of Si rails and slot shift on the device＇s performance, were analyzed and the optimal design was given. Moreover, the influence of fabrication tolerances and the loss of device were both investigated. Compared with state-of-the-art tunable MRRs, the proposed electrically tunable micro-ring resonator owns the excellent features of wider tuning ranges, larger FSRs and ultralow voltages.