Near-field Modulation Research Articles

Transmitter Architectures Based on Near-Field Direct Antenna Modulation

A near-field direct antenna modulation (NFDAM) technique is introduced, where the radiated far-field signal is modulated by time-varying changes in the antenna near-field electromagnetic (EM) boundary conditions. This enables the transmitter to send data in a direction-dependent fashion producing a secure communication link. Near-field direct antenna modulation (NFDAM) can be performed by using either switches or varactors. Two fully-integrated proof-of-concept NFDAM transmitters operating at 60 GHz using switches and varactors are demonstrated in silicon proving the feasibility of this approach.

Cube probe structures for integrated near-field scanner module

Two new miniature near-field 'cube probe' structures for EMC/EMI measurements are proposed. Their performances are compared to those of the classical H-field loop probe in two orthogonal planes. The single cube probe effectively replaces three conventional orthogonally oriented loops. An array of cube probes is also proposed to form a near-field scan module dedicated to the characterisation of integrated circuit radiated emissions.

Near-field modulation of laser diode emissions by an aperture probe of near-field optical microscope

In situ emission profiles of AlGaInP multiple quantum well laser diodes (LDs) observed by a near-field scanning optical microscope (NSOM) probe with an intentionally enlarged aperture shows a single broad elliptic profile, whereas the detected wavelength hops among those of the longitudinal multimodes observed in the far-field. This hopping suggests the near-field coupling between the aperture and the LD cavity, which is proved by the observation of strong modulation of laser intensity by the optical coupling only in the near-field regime. Probes with an intact aperture are found not to couple with the lasing TE 00 mode, but, therefore, couple only with a near-field longitudinal mode. Around the lasing region, emissions detected by an intact aperture are ascribed to amplified spontaneous emissions at wavelengths far from those of the lasing multimode emissions. These near-field modes, with spatial profile different from both the far-field TE and TM modes, are detectable only by the NSOM.

Fiber-Lens-based Module for Optical Recording Applications

An optical fiber-lens-type pickup with numerical aperture (NA)\\cong0.27 was demonstrated for thermal recording of continuous 1.6-µm-wide lines on MO disks with 50% throughput efficiency. Moreover, a Si-micromachined near-field module integrated with a fiber lens, solid immersion lens (SIL), and submicron aperture was fabricated to improve the mechanical fragility and increase the NA of the optical-fiber-based pickup. The preliminary configuration design and measurement suggest the feasibility of the module as a submicron heat source for high-density optical data storage.

Modulation imaging in reflection-mode near-field scanning optical microscopy

A simple implementation of modulation of the near-field optical signal of near-field probes based on the shear-force feedback system is demonstrated in a reflection-mode near-field optical microscope. The modulation exhibits a derivative type of dependence on the near-field signal and no sensitivity to topography. It is shown that the modulation image can be calculated directly from the derivative of the conventional near-field scattering image. This type of near-field modulation is an excellent way to reject far-field artifacts from the near-field signal.

Near-Field Laser Intensity Modulation SIL MO Recording in TbFeCo Magneto-Optical Media.

A high numerical aperture Near-Field laser intensity modulation solid immersion lens magneto-optical (SIL MO) recording system based on a near-contact flying SIL slider setup is described. It is shown experimentally that effective numerical aperture as high as NA=1.46 could be achieved using the contact recording mode and a high refractive index supersphere SIL lens. MO marks as small as 150 nm FWHM recorded using laser intensity modulation technique are observed using the MFM. Recording characteristics of Near-Field SIL MO system are discussed.