According to the principle of Faraday effect,the magnetic field can be measured with the polarization dependent loss (PDL) of the fiber Bragg gratings FBG. The polarization of light is changed by the liner birefringence existing in(FBG). The intrinsic PDL in the different structure gratings is simulated and measured,and the validity of the result is proved. The change of the state of polarization with the magnetic field and birefringence is theoretically analyzed and simulated by using the Jones matrix. The influences of liner birefringence and polarizing angle on the measurement system are compared. The peak of PDL and the cross sensitivity of the system vary with different polarizing angle. The linear relation between the magnetic field and the peak of PDL is not affected by these factors.

The limitations of current interferogram reduction software with circular Zernike polynomials in analyzing obstructed interferogram are illuminated. The Zernike circle polynomials are no longer orthogonal over an annular region and have no explicit physical meanings. The Zernike annular polynomials are discussed and illustrated,which have orthogonality and the similar natures with the Zernike circle polynomials. The experiment is carried out with a Φ 300 mm aspherical mirror with 0.23 obscuration by null-compensation,and the obstructed wavefronts are fitted with Zernike annular polynomials. The first four terms are regarded as misalignment errors and eliminated from the original phase distribution directly,and thus an accurate surface map is gained,which provides a guarantee for the superprecision fabrication.

Two-stage cross dipole fractal slits are sample is fabricated by electron beam lithography (EBL) and reactive ion etching (RIE) system,and the width of the fractal slits is about 0.12 μm.The primary and secondary cross dipole arm lengths of the fractal unit are 1.8 μm and 0.8 μm,respectively.The overall size of the sample used in the experiment is 35 μm×35 μm,which is composed of 20×20 periodic array of two-stage cross dipole fractals.The period of the fractal lattice is 1.5 μm.The transmission spectrum of the two stages cross dipole fractal slits is simulated using the transfer-matrix method (TMM) in the near- and mid-infrared region.There are two enhanced transmission peaks at 1.7 μm and 5.2 μm with the transmission coefficient of 36% and 49%.The measured transmission spectrum agrees well with the simulation.

Optofluidics chips have the advantages of miniaturization,integration,and reconfigurability.The technique on actuation of liquid often becomes the bottleneck in the research of optofluidics.The property of minim liquid is different from that of bulk liquid,so new techniques on actuation of liquid using microcosmic characteristics are researched.They are more miniaturizing,integrating and flexible than the macro-techniques.Some new techniques by using surface tension,heat,radiation pressure,Marangoni convection,magnetic field,and the interaction between liquid and electromagnetism on actuation of liquid of optofluidic chips are described.

In order to improve the beam quality of laser diode (LD) side-pumped solid laser and increase the efficiency of mode TEM00,a ring LD arrays (LDA) non-uniform pumping mode was reported. Two crisscross semicircular LDA were used to side pumped two laser rods and were cooled by heat conduction at the other face. The optical rays from LDA were regarded as Gaussian beam approximately. With computer modeling in the conveyable regulation of Gaussian light,the pumping uniformity characteristics in crisscross semicircular LDA non-uniform side-pumped Nd:YAG laser were studied. The influences of pumping uniformity was analyzed at different distances and absorption coefficients.

Heat sink with the adiabatic groove is used to improve the asymmetry of the thermal focal length of laser-diode (LD) corner-pumped composite slab lasers. The numerical analysis indicates that the thermal focal length of two directions can be equal when the size of groove is 0.325 mm×2 mm×14 mm. The experimental results show that the difference of the thermal focal length of two directions decreases from 3.86 times to 2.19 times when the heat sink with the adiabatic groove is employed. Finally the calculation considering end effect and improving process precision of groove is put forward to further improve the asymmetry of thermal focal length.

Temperature distribution of diode arrays in different fill factors and cavity lengths operating at the same continuous-wave output power is simulated. And the influence of diamond sink and both sides cooling on the thermal distribution of arrays are discussed. On the base of the theoretic analysis,using large waveguiding structure,2 mm cavity length and high fill factor of 80%,continuous-wave output power of 176 W is achieved.

The transient processes of temperature rise and fall exist in laser crystal pumped by quasi-continuous-wave (CW) laser diode (LD).In order to solve thermal effect of laser crystal end-pumped by quasi-CW LD,a general analytical transient temperature filed expression of Nd:YAG rod end-pumped by the quasi-CW supper-Gaussian beam is obtained by the methods of eigen-function and constant variation,based on the heat conduct equation.Meanwhile,the influence of the quasi-CW pump beam with different waist radii,pulse widths and frequencies on the transient temperature filed of Nd:YAG rod,are quantitatively analyzed.The results show that for quasi-CW LD end-pumped Nd:YAG rod,the temperature of the rod has sawtooth distribution with time,which shows periodically stable distribution after some time,and it increases with the increase of the pump width or pump frequency.The research methods and results can also be used to analyze other transient thermal problems in laser systems.

For high precision size measurement of parts,the synchronization of linear array CCD camera image acquisition and parts movement is researched.The synchronization method using servo motor and motion control card is analyzed,and a control method is proposed with asynchronous motor and encoder.The relationship between the motion control system and the camera line rate is studied,and synchronization control of unequal step is designed.According to image acquisition characteristics of linear array camera,diameter parameters on chip direction and motion direction of a standard circular target is extracted,realizing calibration of object image ratio and interpolation correction factor.A linear interpolation algorithm is designed that any shape of the target imaging can be corrected according to correction factor.Experimental results show that the method can effectively correct image deformation of tension for linear array CCD with low cost.

By means of hybrid refractive-diffractive structure,a kind of three-elements telephoto lens based on two kinds of ordinary homebred glass K9 and TF3 has been designed. The working wavelength range of the system is 0.546~0.768 μm. The secondary spectrum has been revised. Its optical performances are compared with all refractive ones which are made of seven pieces of optical elements and four kinds of glass. The results show that hybrid refractive-diffractive lens can effectively eliminate the aberrance of telephoto lens and greatly reduce system length,weight,and complexity. The optical imaging and structure performances of hybrid refractive-diffractive telephoto lens are superior to all refractive system.

The high speed coaxial laser diode assembly with data rate up to 10 Gb/s and transmitting distance up to 10 km is studied. Based on the in-depth analysis of the key characteristic inside the assembly covering from optical structure to high frequency electrical performance,and after a series of optimized design,the transmitter optical sub-assembly (TOSA) has been developed successfully,which can be directly adopted by 10 Gb/s small factor XFP transceiver. The final test shows that better than 7 dB extinction ratio and margin of more than 15% at 10.709 Gb/s are obtained,which keeps well compatible with the one of those advanced level products over the world.

Based on the accurate definition of light intensity of nonparaxial scalar beam at the transverse plane,a detailed numerical calculation of the beam widths,far-field divergence angles,and M2 factors defined by the power in the bucket (PIB) and second-order moment are performed for nonparaxial scalar Gaussian beams,and the result is compared with that of paraxial scalar Gaussian beams.The results show that the far-field divergence angle and M2 factor defined by the PIB are less than those defined by second-order moment.Both M2 factors tend to zero as beam waists vanish.The beam widths,far-field divergence angles,and M2 factors defined by the three definitions have great differences when the parameter of beam waist w0 is relatively small,and the beam parameters tend to unity with the increasing of w0.The relationship between the beam waist parameter w0 and the validity of the second-order moment theory of paraxial and nonparaxial scalar Gaussian beams are pointed out.This will provide reference for the study of the propagation characteristics of nonparaxial beams.

Two of three two-level atoms which are initially in the W state are injected into two empty cavities respectively to have resonant interaction with the light field.The dipole squeezing of the two atoms inside cavities under a rotation operation and direct selective maeasurement are compared numerically.The influences of the manipulation and state-selective measurement of the atom outside the cavities on the dipole squeezing of the atoms inside cavities are discussed.The results show,the dipole squeezing of atoms inside the cavities can be controlled by the manipulation of the atoms outside the cavities; when the rotation angle increases from zero to π/2,the term of amplitude Sx displays a changing process from squeeze strengthening to weakening.It indicates that the dipole squeezing of the atoms inside the cavities can be controlled by the manipulation of the rotation angle of the atom outside.

From the viewpoint of the time-varying general characteristic of various disturbances,categories of the fiber-optic disturbance distributed sensing technology are presented. The system structures,detection principles,location methods,characteristics and application fields of fiber-optic time-varying disturbance distributed sensing (TDDS) technology are analyzed. Two common kinds of the TDDS technology called optical time domain reflectometry (OTDR) and interferometer are introduced in the round. A novel chaos active fiber-optic TDDS technology is described in detail,and the principles,advantages and disadvantages of the location methods of various TDDS research schemes and the last location methods are emphasized. Finally the directions of promoting wide application of the fiber-optic TDDS technology are proposed,which improve the real-time properties and anti-jamming ability and reduce the false alarm ratio of the TDDS system.

The reported intensity-demodulated fiber Bragg grating (FBG) sensors are reviewed and classified into four types including the matched FBG method,filtering method,chirped-FBG method,laser matched method and radio frequency (RF) signal measurement method. The principls of these methods are introduced. Both the advantages and disadvantages of these methods are also discussed. And the development of intensity-demodulated FBG is forecasted.

In recent years,laser diode pumped alkali laser (DPAL) has obtained a rapid development which has great potential to become a new kind of high-energy laser.But the absorption linewidth of the alkali atom even with proper one atomspheric pressure of buffer gas is difficult to exceed 100 GHz comparing with the 1000 GHz linewidth of the commercial diode laser.In order to pump the alkali laser efficiently,the high power frequency narrowed diode laser is needed.On the basis of the principle of laser diode pumped alkali laser,different ways to narrow the linewidth of high power diode lasers are introduced,the characteristics of each method are compared and a review on expectation and development for high power frequency narrowed diode laser is made.

In conventional chemical oxygen-iodine lasers (COIL),molecular iodine is injected directly into the main gas flow of singlet delta oxygen. Then ground state atomic iodine is obtained by the dissociation of molecular iodine with the consumption of energy of singlet delta oxygen molecules. This way of atomic iodine generation limits the small signal gain,output power,and chemical efficiency in the developments of COIL. In contrast,an alternative technique of injecting atomic iodine directly can not only avoid the above metioned drawbacks,but also broaden the application field of COIL. Recently,a great deal of efforts are devoted to new methods in which the ground state atomic iodine is produced by either discharge dissiciation or chemical reactions. The histroy of atomic iodine generation developments and recent research progress of atomic iodine generation by electrical discahrge methods and chemical methods are presented. The critical techniques of atomic iodine generation are summarized. The development trends are predicted and problems needed to be solved are pointed out.

The improvement of the uniformity of on-target irradiation has long been a critical task for Inertial confinement fusion(ICF) laser driver.A number of smoothing techniques have been developed in the past decades.Spatial techniques can control the target spot envelope and improve the irradiation uniformity of large spatial scale,while temporal techniques can smooth the beam by eliminating intensity modulation of short wavelength inside the spot.A comprehensive review on this field is made,and a brief introduction of the smoothing requirements for the facility “SG Ⅱ” is given,as well as the development of smoothing techniques used in it.

In the field of high energy density physics (HEDP),the structures,characteristics and evolutions of the matter with the energy density of 1011 J/m3 are researched. HEDP plays an important role in inertial confinement fusion,material physics,astrophysics,accelerator physics and national defense. Some developments on HEDP by using femtosecond relativistic laser have been shown,including electron acceleration,ion acceleration (proton and heavy ions) and others interesting results.

High energy density physics(HEDP) is a rapidly growing frontier field,in which new physical phenomena are rich and important applications have been applied or prospected. The matter of high energy density is normal in universe. However,with the developments of high-power laser,Z-pinch,and ion accelerator facility,it is feasible to create such matter in laboratories. New developments and important scientific problems of high-power laser-based HEDP particularly on the fast ignition of inertial confinement fusion and laboratory astrophysics are briefly introduced.

Studies on simple atoms and molecules in ultrafast intense laser field explore abundant physical phenomena and provide basic physical information for extreme physical processes under the condition of high energy density.We mainly introduce some experimental and theoretical studies on polyatomic molecules in a femtosecond laser field from our laboratory recently,including ionization/ dissociation of polyatomic molecules in femtosecond laser,ultrafast energy transfer of excited molecules in solutions,and controlling the ablation by shaped femtosecond pulsed laser.