Ming Li

US Patent:

6433305, Aug 13, 2002

Filed:

Dec 26, 2000

Appl. No.:

09/747682

Inventors:

Xinbing Liu - Acton MA
Ming Li - Storrs CT

Assignee:

Matsushita Electric Industries Co., Ltd. - Osaka

International Classification:

B23K 2602

US Classification:

21912171, 21912169

Abstract:

A method of laser machining using an ultra-fast pulse laser is presented. According to the present invention a plurality of holes with a pitch less than the wavelength of the laser are drilled into a material sample. Reliable and reproducible hole drilling is accomplished through an exemplary drilling sequence which applies a number of pulses at a first pulse energy to the surface spaced to avoid laser hardening of the surface for adjacent holes of a first set of holes. Next, the number of pulses is increased or the energy of the laser beam is increased to drill holes that are interstitial to the first set of holes. The exemplary laser machining process may used to produce both one-dimensional and two-dimensional photonic crystals, among other applications.

US Patent:

6529307, Mar 4, 2003

Filed:

Jun 4, 2001

Appl. No.:

09/874474

Inventors:

Song Peng - Pleasanton CA
Ming Li - Pleasanton CA

Assignee:

Avanex Corporation - Fremont CA

International Classification:

G02F 103

US Classification:

359256, 359315, 359319, 359245, 359250

Abstract:

A method and apparatus for achieving dynamic intensity modulation of the channels in a wavelength-division multiplexed optical communication system is presented. Wavelengths are spatially separated into a plurality of channels, the polarization states of which are individually modulated. The channels can be combined or filtered by polarization states to achieve the desired intensity in the output signal. An exemplary embodiment includes at least a polarization modulator, a birefringent wedge, a lens, and a dispersive element (e. g. , diffraction grating) arranged in various order. Each segment of the polarization modulator can be made to rotate the polarization direction of an incident channel by a specified angle. A half-wave plate may be inserted between the second dispersive element and the second birefringent wedge to eliminate polarization-dependent loss. Optionally, a parallel birefringent plate may be inserted after the second birefringent wedge to reduce polarization mode dispersion.

US Patent:

6546159, Apr 8, 2003

Filed:

Aug 22, 2002

Appl. No.:

10/225650

Inventors:

Song Peng - Pleasanton CA
Ming Li - Pleasanton CA

Assignee:

Avanex Corporation - Fremont CA

International Classification:

G02B 600

US Classification:

385 11, 356399, 2502014, 349 77

Abstract:

An improved digital differential group delay (DGD) controller is capable of producing variable DGD used to compensate for DGD in a fiber optic link in real time. The DGD controller comprises one or more sets of a polarization modulator optically coupled with a fixed delay component, such as a birefringent plate. Each set provides an amount of DGD compensation. By controlling the number of stages in the controller, the amount of DGD compensation provided by each stage, and which stages are placed in the ON state, the total amount of DGD compensation provided by the digital DGD controller can be varied.

US Patent:

6556306, Apr 29, 2003

Filed:

Jan 4, 2001

Appl. No.:

09/754183

Inventors:

Zhiping Jiang - Ottawa, CA
Ming Li - Cupertino CA

Assignee:

Rensselaer Polytechnic Institute - Troy NY

International Classification:

G01B 902

US Classification:

356517, 356487

Abstract:

A non-contact, free-space method for determining the index of refraction of a thin film at a desired angular frequency. The method includes generating an input desired-frequency pulse and an optically detectable probe pulse. The thin film is moved in and out of the path of the input pulse, creating an output pulse that alternates between a transmitted signal, created when the film intercepts the input pulse path, and a reference signal, created when the sample is outside the input pulse path. The output pulse modulates the probe pulse, which is then detected with a photo detector, and the difference between the transmitted signal and the reference signal is calculated. The above steps are repeated over a plurality of delay times between the input pulse and the probe pulse until a complete field waveform of the differential signal is characterized. The index of refraction is calculated as a function of a ratio between the differential signal for the thin film and the reference signal. A complete field waveform of the reference signal may be characterized by repeating the above steps for a reference plate identical to the sample except having a non-transmissive film instead of the thin, transmissive film.

US Patent:

6570122, May 27, 2003

Filed:

Jan 3, 2002

Appl. No.:

10/038330

Inventors:

Xinbing Liu - Acton MA
Ming Li - Storrs CT

Assignee:

Matsushita Electric Industrial Co., Ltd. - Osaka

International Classification:

B23K 2638

US Classification:

21912171

Abstract:

A method of laser machining using an ultra-fast pulse laser is presented. According to the present invention a plurality of holes with a pitch less than the wavelength of the laser are drilled into a material sample. Reliable and reproducible hole drilling is accomplished through an exemplary drilling sequence which applies a number of pulses at a first pulse energy to the surface spaced to avoid laser hardening of the surface for adjacent holes of a first set of holes. Next, the number of pulses is increased or the energy of the laser beam is increased to drill holes that are interstitial to the first set of holes. The exemplary laser machining process may used to produce both one-dimensional and two-dimensional photonic crystals, among other applications.

US Patent:

6594082, Jul 15, 2003

Filed:

Feb 26, 2001

Appl. No.:

09/794590

Inventors:

Ming Li - Pleasanton CA
Song Peng - Fremont CA

Assignee:

Avanex Corporation - Fremont CA

International Classification:

G02B 2600

US Classification:

359618, 359290, 385 11

Abstract:

An optical wavelength router utilizes a dispersive medium (e. g. , a diffraction grating) and reflective surfaces. The dispersive medium separates an input optical signal (light beam) into a plurality of components, for example by wavelengths. The reflective surfaces convert the components into separate output beams traveling in the desired directions. The number and the direction of the output beams can be controlled by manipulating the angle of incidence at which the components strike the reflective surfaces. A micro-mirror array modulator serves as the reflective surfaces. Each mirror in the micro-mirror array modulator is positioned to direct individual components into a number of output signals. Alternatively, a polarization steering device which includes a polarization modulator and at least one birefringent element in addition to reflective surfaces is utilized. A Wollaston prism with a reflective surface may also be used.

US Patent:

6621045, Sep 16, 2003

Filed:

Oct 8, 2002

Appl. No.:

10/266936

Inventors:

Xinbing Liu - Acton MA
Ming Li - Chelmsford MA
Chen-Hsiung Cheng - Chelmsford MA

Assignee:

Matsushita Electric Industrial Co., Ltd. - Osaka

International Classification:

B23K 2638

US Classification:

2191217

Abstract:

A method is provided for maintaining a workpiece in a focal plane of a laser drilling system. The method includes: providing a workpiece holder that is adapted to releasably retain a workpiece on a planar surface thereof, the planar surface having a recess extending therein; positioning the workpiece onto a planar surface of a workpiece holder, such that the workpiece extends across the recess formed in the workpiece holder and an exposed surface of the workpiece aligns with a focal plane of a laser drilling system; projecting a laser beam from the laser drilling system onto the exposed surface of the workpiece, thereby forming an ablation on the exposed surface of the workpiece; and directing a flow of gas onto the exposed surface of the workpiece substantially concurrent with the step of projecting a laser beam, such that the flow of gas substantially impinges on an area of the exposed surface that extends across the recess formed in the workpiece holder, thereby maintaining the exposed surface of the workpiece in the focal plane of the laser drilling system during the laser drilling operation.

US Patent:

6710288, Mar 23, 2004

Filed:

Oct 8, 2002

Appl. No.:

10/266944

Inventors:

Xinbing Liu - Acton MA
Ming Li - Chelmsford MA

Assignee:

Matsushita Electric Industrial Co., Ltd. - Osaka

International Classification:

B23K 2603

US Classification:

2191217

Abstract:

A method is provided for aligning a workpiece in a laser drilling system. The method includes: providing a workpiece having at least two substantially planar and parallel surfaces, including a first planar surface in which ablations are formed therein by the laser drilling system; propagating an alignment beam of light towards a second planar surface of the workpiece, the alignment beam being incident on and reflected by the second planar surface, thereby forming a reflected beam of light; measuring a reflection angle of the reflected beam; and determining alignment information for the workpiece based on the measured reflection angle of the reflected beam. The method may further include adjusting alignment of the workpiece based on the alignment information.